How to increase gas mileage by 39%, or why the truckers are going to be pissed

I watched a recent episode of Mythbusters, and it dealt with the myth that drafting behind a big rig drastically increased fuel economy.

Tests in a wind tunnel showed a lot of promise, with drag reductions at 93% when the model car was a scale two feet back from the model truck.

Tests on the road during controlled circumstances showed the following results:

100ft 50ft 20ft 10ft 2ft
11% 20% 27% 39% 28%

for 55 miles per hour.

Presumebly the faster the truck goes the bigger the dead spot behind it. But staying one second or less behind a big rig will increase your fuel economy by a substantial amount.

I predict a lot of angry truckers screwing with drafters in the future! :-)

http://en.wikipedia.org/wiki/MythBusters_%28season_5%29#Drafting_For_Money

But hey! Knock yourself out.

Pa - dum - pum.

I did car crash insurance defense law for 10 years. 100 feet is too damned close at any realistic speed. At 65 mph, you're talking at least 180 feet to stop. And that's AFTER you react to the truck's red lights and fishtailing rear wheels. Reaction time is going to be somewhere like .7 second. So 5280 divided by 60 mph (1 mile per minute), you're traveling 88 feet per second. If you don't even hit the brakes until .7 second after the red lights come on, now you're 61.6 feet closer to whatever made the truck brake. If it takes 2.5 seconds to stop, you've probably hit the rear of the truck before you can stop.

My advice: If you're going to draft trucks closer than 180 feet at 60 mph, be sure you have your will written and witnessed by two competent adults, and your kids aren't with you.

IT'S REALLY STUPID.

While i agree with you that it's really stupid, your math doesn't include the fact that the mass of the truck is such that it takes longer to stop than a car. So, unless the truck comes to an instantaneous stop at 55mph (impossible, of course), there is actually a wider interval before you hit the truck.

Still, i wouldn't do it either.
GAC

Trucks having a greater mass have a greater normal force, thus a greater breaking force. In ideal conditions stopping distance is independent of mass. Obviously that doesn't hold up in all real world situations, but trucks can brake a lot faster than most people think they can.

And don't assume. I know exactly how the physical concepts of newtonian force work. The breaking power of a big rig, plus the added frictional forces of the mass on fixed tires, do not compensate for the 30x difference in mass.

And stopping distance is never indepedent of mass. f=ma, right? So, the amount of force is not independent of mass but purely a function of it. In this case, "a" is a negative value, but m is still a leveraging value.

In addition, my dad drove semis for decades and i know more about truck driving than i ever wanted to.

You'll just have to trust me on this. I didn't forget anything, and i know what i'm saying is true.
GAC

Because from a Newtonian standpoint, stopping distance (d) is independent of mass

d = (v^2)/(2 * coeff. of fric. * g)

Sorry. You're cherry picking equations. The distance is a function of force. Overcoming the existing inertia of the truck is measure in newtons and joules. Newtons include mass.
GAC

And braking force, also measured in newtons although it doesn't really matter what you call it, also depends on mass. And the masses cancel out.

The distance is function of the force applied by the brakes. That's the only thing that matters in decelerating an object. You're obfuscating with tangential elements of the equation that are still part of the parcel of the force equation. The force equation, the most fundamental thing in newtonian physics, is a function of mass. Your earlier equation is a vector of f=ma. You can slice it however you wish, but it's still all derivative of f=ma.
GAC

and the coefficient of friction between the tires and the road. F=Nµ_k, which in the case of a flat road reduces to F=mgµ_k. m is the mass of the truck, g is earth's gravity, m*g is the normal force (assuming a flat road) and µ_k is the coefficient of kinetic friction.

In theory, if Truck A weights twice that of Truck B, it will have twice as mush kineticn energy and momentum. It will also have twice as much braking force to act on it's twice as much mass, so the decceleration should be the same.

However, as the tires heat up they melt and lose traction, not to mention that it will take a little longer to bring the tires up to full braking force, time that transforms into distance. Panic-stopping twice as much mass will heat the tires up faster, causing less stopping friction and thus less decceleration.

Of course, I'm assuming wheel lockup by using the µ_k. If the big rig has anti-lock brakes, the coefficient of static friction, µ_s is used instead, which is significantly higher and thus imports more braking force is the driver or the ABS is able to hold the braking force right at impending lockup. This is why anti-lock brakes are such a critical safety features.

Likewise, if the following car has ABS, it will be able to stop much faster than, say, my old beater does.

The breaking force is a function of the shoes gripping the rim, not just of the tires on the ground. Unless a larger object has an proportional amount of decelerating forces on the wheels themselves the difference on the ground is less important. So, having twice the mass doesn't work unless the wheels are capable of completely LOCKING UP when force is applied. At enough speed, getting all the wheels on a semi-tractor to lock simultaneously is mechanically difficult and requires massive hydraulic or pneumatic force.

The heavier the object, the more rotational momentum, since something that weighs 30 times as much doesn't have wheels 30 times larger in circumference. That lost surface area requires a compensation of greater force to stop the wheel.

In addition, we can debate this all we want, but if you've never seen the length of skid marks from a truck accident, it's all academic. My dad was in one when another semi jackknifed in front of him. His skidmarks were WAY, WAY longer than any of the cars behind him. They were all stopped at least 50 feet behind where hit the other truck.

BTW: He was essentially ok. Broken collarbone and broken patella. But, otherwise survived just fine. And you know what? A semi full of milk makes a BIG mess.
GAC

It would also take twice the pressure on the brake drums or rotors to make twice the braking force. Something that might not be achievable.

I've seen some pretty impressive skidmarks on the highways, but you are correct. There weren't 18 of them!

From the car magazine I read, it looks like most passenger vehicles stop in about 170 feet or so from 70 MPH. I don't know what I big rig does, but I would imagine that, fully loaded, it's somewhat more.

http://www.newton.dep.anl.gov/askasci/phy00/phy00754.htm

On a related note, you get your best stopping distance when you threshold brake, which not everyone knows how to do. ABS comes close though.

...and they don't stop very quickly.

My dad was in a truck accident. He drove a big truck for decades. They do not stop as fast as a car. Cherry-picking physics equations doesn't change that.
GAC

stupid, stupid, stupid.

More people drafting behind trucks = Greater Auto fatalities = Less Drivers overall on the road = More fuel for the sane people.

Nice formula.

I had truckers tell me to do it because it saved gas and they
flashed their lights when there was a speed trap ahead!

Cool people! ;)

worth your life. If you stay that close to a truck you will be in a big blind spot. You also won't have time to stop should the truck have to stop. Some truckers may get pissed but mainly because most would rather not kill someone even if it is the someone's fault.
Also will you save enough to cover a ticket for aggressive driving and following to close? Those are two traffic violations you can get.

Did they say how much you can save by slowing down and maintaining a steady speed?

trucks move slower than speeds I typically drive at on the highway, at least during busy hours. I tried it last night, following a Wal-Mart truck that was doing about 60. I stayed back not quite a second, so I was maybe 75 feet back. By that chart I should have gotten about a 17% increase in fuel economy, plus what I was saving by driving slower than normal.

In light traffic like that it's immediately obvious if the truck is slowing down or doing a panic stop, so I didn't feel unsafely close. And, you know, the needle on the gas gauge barely moved all the way to the drive in. And it's like 30 miles away.

my mom used to do this all the time in Ohio. I constantly worried about her; she couldn't see around the truck while she was tailgating it, so if the trucker had to react to a deer or bad driver she would have plowed right into him (or her). There is no way to react to a real change in speed, even at 20 feet behind a semi.

Remain at a safe distance but you should be able to feel the drag.
There was enough spacing when I've done it. I'm not talking about
heavy traffic or a lot of congestion. Open road!!

on the freeway. Rule of thumb; one car length for every ten mph. On the highway that would mean at least 80-100 feet behind for the average vehicle, giving only a 20% reduction in gas usage. Might be worth it, but getting the 39% reduction in usage at a much higher risk to one's life isn't in my book. And even on the open road a deer can leap into the path of a truck.

I don't drive 80 to 100 MPH on the highway either!!

Where the hell do you drive? I don't want to be there! :rofl:

but never 2-10 feet, more like 50-100 feet. I can still "feel" the assist, even though it's nowhere near 39% or whatever.

I can't do it for long distances, just because it's too much stress, having to be so alert, ready to twitch on the brakes. And it blocks the view of the scenery. It's more relaxing to leave a lot of distance in front.

A deer jumps in front of a truck? I hope the truck driver just keeps rolling, controlling the vehicle. Smashing into a deer is probably less damaging to a semi than slamming on brakes and risking losing control. And then hit the deer anyway.

which will decease the truck's lousy MPG which is already low enough.

You don't get something from nothing. You're essentially robbing Peter to pay Paul. Shifting costs to the other party. If you weren't posting to DU, I would have to swear this was a another dumb Rupug plot to resurrect a failed economic policy.

Actually I did this test once myself, by following a truck loaded with sand. I could physically see the sand being pushed off the top of the bed of the truck, so I could estimate where the draft position would be.

You essentially have to kiss the rear bumper of the truck to escape the wind drag of the vehicle ahead of you. Unless you are mechanically-attached to the frame of the truck's bumper, essentially your reaction-time for braking would need to be instantaneous (or better than instantaneous) to avoid the rear-end collision.

It's not worth the risk. Better to buy a Toyota Prius or some hybrid car and drive safely on the highway.

I don't believe this for a second.

BOTH vehicles with speed and gas mileage.

Every indy driver has known since birth that drafting helps both vehicles, because the second vehicle helps reduce drag on the first, at the same time as the first car pushes the air out of the way, helping create a draft for the second.

With odd sized vehicles, (say a truck and a car) the amount of drag reduction for the front vehicle, say the truck, is lower.

are you saying, then, that an infinitely-long vehicle will have an infinitesimally-small drag and improved MPG? If you put a sufficient number of cars following behind the truck, then according to your logic, it would remove the drag or reduce the drag from the lead vehicle (the truck).

It would seem logical that the longer the vehicle, the longer the drag. And a longer drag will result in reduced MPG.

Also, there is the law of diminishing returns that probably has to come into play somewhere along the line.

The bottom line, IMHO, is that you don't get something for nothing.

But even if what you're saying is true, it is a foolish and unnecessary risk to tail-gate a truck at +60 mph on the highway.

The best solution is to try and become mechanically-attached to the truck's rear bumper with some kind of super-magnet. In which case, you can turn off your engine and let the truck pull an extra ton or two to get yourself a true 'free ride'. Until the driver gets wise to the game and pulls over.

One car can be way ahead of the pack. WAY AHEAD. If a number of cars get themselves nose to tail, and work together, it's nothing for them to achieve a greater speed (due to reduced drag for ALL of them) and run down the leader and pass him like he's standing still. Additionally, if ONE car gets out of a long line, he goes to the back of the pack due to lack of "the draft".

I'm not smart enough to do the math, but I know this to be true because I've seen it with my own eyes more times than I can remember.

A large portion of the drag is caused when the flow separates from the car body at the rear and fills the lower pressure area caused by the car displacing the fluid. This is why cars have narrow rears, with the trunk necking down and inward in many models, as this leaves as small of a low pressure region as possible when the fluid separates from the car body. Drafting very close in racing reduces the low pressure area, hence reducing the drag on the car in front and the on the following car.

On a truck, the effect would be hardly noticeable. The seperation area is too big to be negated by a car following, and the gain for the car will not impact the truck.

To put in in real simple terms, he's your blocker, and he takes the brunt of punching through the defenders whether or not you follow him into the end zone.


On edit: Trunk, not truck

I mean, comparing the drag between NASCAR racing cars on a track and tractor-trailers on the interstate is apples and oranges, to say the least.

I would rather go for the super-magnet to attach my front end to the truck's rear bumper. At least the braking wouldn't be the problem. Ground clearance of obstacles would be the biggest worry, as trucks have higher ground clearance and the debris would possibly end up somewhere in my vehicle's chassis, tear up the tranny, radiator, ect.

You push the air out of the way, and it collapses again. When you do this,
Behind you is a low pressure area that pulls you back.

You can both each push the air out of the way, or you can only do it
once. Doing it only once is less work.

If you ride in the bubble behind the truck, you share that, so you
both don't have to push the air out of the way, the truck does most of that,
and the truck doesn't deal with the vacuuum, because you are keeping
the air between you and him from forming a large pocket of low
pressure by bouncing some air at his back.

The drag does not occur on the sides of the vehicle (laminar friction)
That accounts for only a tiny percentage of the air resistance. Most
of it it air colliding head on with the front, and negative pressure
on the back.

Very long vehicles are called trains. They are extremely efficient
both due to the air resistance being much less per car, and the low
rolling resistance of steel on steel.

Now if you want something really mind boggling, check
out these:

http://autospeed.drive.com.au/cms/A_3061/article.html

Therefore, gas mileage may not matter when you run up under an 18 wheeler and eat some axel.

<drool>

Actually, most people seem to stay pretty close to the ass end of trucks anyway. That distance will give you 10-15% more economy. Trying 50 feet or less is just suicidal. But most people in moderate or worse traffic routinely leave less than a second's worth of distance between themselves and the car in front of them.

Following distance is (roughly) speed in MPH times 1.5 times number of seconds you are behind. 60 MPH is about 90 feet per second.

anyone with a halfway decent reaction time shouldn't have any problems.

Good luck with that.

and my brother-in-law from edmonton does it all the time, too.

What you just posted is careless and irresponsible. What if an 18-year-old "new driver" were reading this, and saw your post? would you feel comfortable with such taking your pathetically ill-conceived advice?

What you're advocating is extraordinarily dangerous. Just the fact that you're (apparently) saying people can safely do this make you not worth listening to, because only a complete and total fucking idiot of the very highest order- the sort I'd be happy to yank their license from- would follow a big rig closely enough to improve his gas mileage.

And if you're doing it with passengers in the car, you're showing careless disregard for human life. Fucking shame on you in any case, and welcome to my ignore list.

whether you care to admit to it or not.

and it's not all that dangerous, because CARS STOP A LOT QUICKER THAN 18-WHEELERS.

you have .25sec to begin to stop...so...a truck hitss the breaks, hard and you have 1/4 of a second to react or you are toast...

sP

a truck hitting the brakes does not stop on a dime. not hardly.

because if that big rig is not loaded and hits the brakes hard he can generally stop as quickly if not faster than you...your reaction time will be in the range of a second before you note that the brakes have been hit and then you have to get your foot from the accelerator to the brake and begin to press the brake which can add another second to a second and a half...

So...2 1/2 seconds...that's 200 feet at only 55 mph... If you are braking from a 20 foot distance you have zero chance if the big rig brakes hard...if it brakes gently...they yeah, you could do it.

sP

neither of us has ever had any kind of mishap because of it.

it's a common practice in some areas- and the truckers don't mind it either.

me too.

there won't be enough of you left to post on DU...keep it up, endanger everyone on the road...

sP

<sarcasm> Bruce Willis would go for that. And so can you. </sarcasm>

You tuck that down to 18 inches and they can't even see you're there.

SPEED


THINKING DISTANCE


BRAKING DISTANCE


OVERALL STOPPING DISTANCE


60 mph


60 ft. (18 m)


180 ft. (55 m)


240 ft. (73 m)

http://www.hintsandthings.co.uk/garage/stopmph.htm

and how they don't stop all that quick- especially compared to a much lighter automobile...?

That factor needs to be taken into account in the equations. It's not like a stationary obstacle.

starts plowing into a line in front of him :P. I really don't have an opinion on this one. There are just so many factors in each particular situation that it would be difficult to come up with a reasonable solution that satisfied all conditions.

a truck going 60 mph slams on it's brakes and a car following 20 feet behind it is going to have the reaction time to stop without hitting it? No that just doesn't work given the distance when one does the math.

Suppose the distance is 20ft. And you and the truck are going 55mph. Now, if you had 20ft to stop, with a wall in front of you, that would not be enough. But the point is that the truck in front of you is not a stationary wall, it's a moving wall. As a matter of fact, the wall moves at 55mph away from you, just before braking, and gradually slows down as the brakes are hit. Because of the truck's inertia, the speed will decrease relatively slowly. In practice, you'd have a wall that moves in front of you at decreasing speed. So, as long you decelerate faster than the truck you're OK. I did not do the calculation, but there may be sufficient time to avoid a collision (you'd have to assume the deceleration rate of the truck etc)...
Not to say this would be a wise thing to try...

But due to the delay between the trucker hitting his brakes and you hitting your brakes, your superior curve starts a bit later than his inferior curve.

At fifty feet behind a truck, you have about a half second before you hit the point where the truck had applied it's brakes. You have to leave enough room for your car to move in closer while you react and start applying your superior braking curve.

:eyes:

Who needs the laws of physics when you can have a ridiculously ironic screenname?

By the way, I once knew someone who smoked for 50 years without incident!

That means cigarettes are harmless too. Yup.

A turkey is born at a farm. He is hand raised by the farmer, played with by the kids and given all the food he can eat. The family dog protects him from coyotes that come sniffing around looking for a meal.

The turkey must think he has it made. Food, protection, love, and he should think this will go one forever.

Then he wakes up the day before Thankgiving to see the farmer walking to his pen with an ax.

(Moral of the story - just because things have worked out in the past does not mean they always will)

(I stole this story from a book I'm reading)

and we all know how well that works out in traffic... :eyes:

Some improvements in mileage aren't worth it.

I've ended up squished behind a big rig once or twice in heavy traffic. The way the draft flaps your car around is no fun and playing possum with an 80,000# death machine? No thanks.


I say we spread this around though. Just think of all the deaths that will cull the stupid people out of society and off the roads. :eyes:

No buffeting that puppy! :-)

Scares the cheese outa me. :)

You Packers fan, you :-)

Truckers were cooperative and there was a "sweet spot" less than 20' off their tail that would actually allow a car to get dragged along in neutral. It was quite amazing.

All cars and trucks, indeed any vehicle, on our roads that wishes to engage in this kind of activity must be capable of being driven by onboard computers. I'm talking about cars that drive themselves and have the capability of calculating real-time road conditions, cars with advanced technology that allows them to navigate roads and negotiate weather conditions.

Indeed, if all cars were on "autopilot" with that kind of capability, thousands of people would not die on our roads due to human error, and if strict laws are passed regulating car maintenance, we would cut down on human deaths due to mechanical/computer failures.

When I think of cars that can drive themselves, I'm thinking of something similar to cars seen in I, Robot with Will Smith where because all cars were driven by computers instead of humans, interstates speeds regularly surpassed 100mph in safety.

I've got my Nissan sedan doing 50 mpg on good days but I would never tailgate a truck. It is just too dangerous. I can't get that close without scaring myself. I've been in too many near misses to risk my life this way. All it takes is one moment of not paying attention and you are a goner. I'll stick to driving slowly and coasting as much as possible.

on your temp gage. If you are really in the right spot, the front of your vehicle is pulled along in a very low-pressure area, and the radiator get no air flow while the engine is almost idling so you can overheat.

if what you're saying is true, 90% of commuters in big cities would blow their engines each trip

It could very easily be 89.314%!

:P

Brr.
There's a lady I chat with at the Y who has lost two (2) of her five grown children in separate car accidents. Her son is in the ground, and her daughter has a very high spinal cord injury and needs 24/7 care and a respirator.

I've always tried to drive carefully, and I like to give big rigs all the room they want. Following them in their wake has always seemed like a real bad idea.

Hekate

as most people have little concept of driving anyway, I figure that anyone who does this on a regular basis is challenging the odds.

For one thing, entire families have been wiped out by practices like this. Another is that no only is the driver of the tailing vehicle placing him/herself in a higher state of anxiety, you're no doing much for the concentration of the lead driver either.

Deer, raccoons, road debris etc, add to hazards that are already inherent on the roads. When you add into the equation that most people are not at optimal condition while driving; age, state of mind, an OTC or Rx med, and above all, other drivers, all mix in to create the dangerous problems we face on the road. Why add more to the mix?

The biggest problem is that you can't see beyond the truck, so you can't anticipate reaction, take your eyes off the rear lights of the truck, (they might not be working properly btw), for a spit second, and you are a mud-flap, maybe taking your family w/you.

Saving a few $'s on gas isn't worth it to me, and shouldn't be for anyone else. In the long run, all this will do is clean up the gene pool a bit, and create snarls as the cops investigate the scene, and the FD is called out to hose the blood and brains off the road...:(

take a sip of coffee,
talk on the cell phone,
take a glance at your kid in the back seat,
fiddle with the radio,
switch to your sunglasses as the cloud over changes,
scratch an itch,
any 100s of other things you can do that will distract you for a split second...

My beloved uncle drove a truck for Safeway for 40 years and he HATED this practice. If you can't see their mirrors, you are too close to stop safely if they use their air brakes.

I don't care if tailgating a truck turns your car into a Prius, it is NOT worth the risk.

I thought the truckers among use might like the forewarning. Mythbusters is a pretty popular show.

I will say in my defense that in busy traffic following times are often within a hundred feet of somebody's rear bumper.

Try it yourself. Time how long it takes you to pass a line or expansion joint after the car in front of you does.

Your velocity in feet per second is your speed in miles per hour times 1.5. At 60mph, you're moving at 90 feet per second.

That is advocating a risky behavior. I wouldn't recommend people try this for even a single drive. It's not worth the risk. I realize that most passenger cars have better stopping distance than any 16 wheeler, but who knows what the 16-wheeler might hit to bring it to an abrupt stop - multi-car pileup? Whatever it is, you will not see it coming because of the truck.

I alerted on this thread, and I honestly can't believe it hasn't been locked.

That nobody with two brain cells to knock together tries to get ten feet off of the bumper of a speeding truck and stay their.

However, being in the 75-100 foot range is fairly common. Before you spend too much time on your soapbox, document how far behind a vehicle you usually drive in various traffic conditions.

If you live near a major city, maintaining a two-second following time is virtually impossible during daylight hours. If you leave a gap that big, somebody will fill it it. Typically it's one second or so, which at 60 MPH is about 90 feet, within the effective range of drafting.

What the research says is that if you maintain a heavy-traffic following distance even when in light traffic, you will continue to save fuel.

And, incidently, if a multi-car pileup happens in front of the truck, I'd be quite happy to let the big rig make a hole for me to pass through. Or at least stop in.

And yeah, sometimes idiots who like to tailgate squeeze in there. Their chances of ending up a bloody pulp of guts and metal shards are MUCH better than mine because of their reckless habits.

You haven't "explained" anything. you've rationalized away a whole lot of facts and stats that show tailgating is extremely dangerous. It's also illegal in many states.


I've followed the 1 second rule for a long time, and I haven't had an accident or moving violation in 18 years. Prior to that, the one accident I did have was caused by following too close on an LA freeway. I was lucky nobody was hurt and the cars were not damaged. It's a mistake I will NOT make again.

I don't understand.

So you stay six seconds behind everybody else while on the highway?

I was always taught by car lengths - you mentioned seconds so I quickly guessed at the seconds.

But my point is that I do keep more space between me and the next car than a lot of people do.

It's easier to time it. I'm not good at estimating distances by eye, and moving cars make it worse.

I let the shadow of the vehicle I'm behind pass a line or expansion joint or pothole, and I'll count "one mississippi", etc. until the same point disappears underneath my hood.

Typically it's 1 to 2 seconds, unless the traffic is pretty heavy. At highway speeds, thats somewhere between 80 and 200 feet.

If you assume a car length is about 14 feet, then 60 mph equals 6 car lengths equals 96 feet.

So it works either way!

And you save 11% on fuel economy...



:-)

Drove from Massachusetts to Florida in a big V-8 Cutlass 2-door. I picked up a truck in Georgia after the last fill up and drafted in much of the way down 1-95 to Central Florida, doing 80 the whole way and I remember being amazed because the gas gauge never seemed to move on the car. But I didn't do the 2-foot version. Probably somewhere between the 20-50 ft mark. It was hairy, bun fun in that adrenaline rush sort of way. Still, they didn't talk about how the car gets buffeted around; you get knocked all over the place, like turbulence in an airplane. And you can literally feel yourself getting "sucked along" by the truck.

I'd never do it again. Probably.

.

A lot farther away than 2 feet but still getting pulled along. Now that I'm older and wiser and have seen too many truck accidents I get anxious around trucks and don't want to be anywhere near them.

I get behind them often on my motorcycle. When you are back about 75 to 100 feet the wind buffeting is very bad. By that I mean that if you're back too far the air becomes very turbulent and that certainly can not be conductive to good fuel economy.

(or however long truckers may drive each day) I'd probably be a pretty big danger to people in front of me as well as the idiots behind me.

Maybe we should draft 2 feet behind a school bus full of kids, too, eh?

LOL!

Plus I drive a little car. The truck could have to stop suddenly and....oops there I go. I'd be smashed. I prefer to keep a good distance away from truckers blind spots.

folks arguing to stay a few feet behind a speeding truck to save a few bucks...

Sometimes on here you just never know. :)

You state in Post #44: "I prefer living over gaining mpg"

Yet you drive a small car, by your own admission, which is more dangerous than drivng a big one in a vehicle collision, in order to get an increase in fuel mileage.

Many people here on the DU advocate people driving small, fuel efficient cars. Prius owners, diesel Volkswagon owners, Honda Civic owners, etc., brag about their milage. About how they're doing their part to reduce their carbon emissions and have less impact on the environment. Yet in any tangle between a Honda Civic and, say, a Chrysler 300C or a BMW 5-Series, the Honda will lose.

People make that choice all the times in the cars they drive. Which is part of the reason SUVs were are continue to remain popular. People that "prefer living over gaining mpg".

Now, I drive a big older car (it was free, so I can't argue with that) but I would happily trade it for a new small car simply because my big old car does not have things like airbags or ABS. I would give up sheer mass for airbags and ABS without a qualm. However, I wouldn't readily give up my big safe car for a small subcompact of the same year that didn't have ABS or airbags.

isn't going to fare well when the truck needs to stop quickly.

I agree that mass it more important, but the innovations in car design over the last few years it shouldn't matter much. The biggest reason with damage in a SUV vs Civic is bumper height. The US make the bumper height standard (there's a it's must be at least this high, but there's not a max height). That's part of the problem.

I drive a 2006 model vehicle, that has electronic stabilization program, ABS and 6 air bags. I feel sufficiently safe driving my vehicle, but not enough to temp fate by driving 5 feet from the rear end of a tractor trailer.

In your case, what your car lacks in sheer mass it gains in better design, airbags, and better brakes.

I would trade my car for yours. I would NOT trade my 1989 Olds Regency 98 for, say, a 1989 Honda Civic unless there were extenuating circumstances. Like, say, my car was on fire. :-)

I think in the US there are new laws that keep SUV bumpers lower to try to avoid this. However with tens of millions of older SUVs on the road, you still run the risk of being badly injured by a truck with a higher bumper.

It does not change the fact that if you had purchased a late model Five Hundred or Crown Victoria or Impala or Charger or 300C, or even a Liberty or Escape or RAV4, you would be even safer.

You made a choice, based on finances and fuel economy, style and comfort, price and warranty, as well as safety. Welcome to real life! :-)

As to the truck thing... I don't tailgate, but hugging a little closer than normal isn't a bad thing. The secret is to not stare at the back of the truck. If you do that you won't notice as quickly if he starts to slow down. Stare past the truck, around the truck, so your sensitive peripheral vision can detect the truck changing speed instead.

I also have excellent depth perception, so I'm very sensitive to speed differences. I can sense with a vehicle in front of me is only two MPH slower or faster.

When there is a strong headwind increases are even more.

Most truckers will just slow down to get me off their ass if it bothers them.

haven't bred yet. The whole Darwinian survival of the fittest thingy - need to get your stuff out of the human gene pool.

for tailgating after you crash. Assuming you're not dead.

interstates. I'm leaving in a little while to drive 700 miles and I will not be taking this advice and hope I don't run into anybody else that is.

Tailgating or even driving just behind the truck in another lane is dangerous.

two other gigantic trucks cover your sides as well. That may mean even MORE savings!

:rofl:

The Venturi effect of high pressure just behind and just in front of you (plus both sides) would suck the air out the center meaning you'd have almost no air resistance. Think how good that'd be! LOL!
GAC

LOL

:D

during the winter when it was cold and I while I was on the freeway. Thing is that you have to be just a few feet behind the bumper of the 18 wheeler to be in the dead spot. It's a little unnerving at first, because as soon as you hit the dead spot the bike surges forward due to the decrease in wind resistance. I always made sure the driver knew I was back there though.

1) Straddling debris. Most drivers with any experience have seen items of various sizes laying in the roadway. Trucks have way more ground clearance than a typical passenger car and will often just straddle debris, whether it is a tire husk, a 4X4 or whatever that might hit the undercarriage or even the front valance of a car. Following too closely makes it impossible to see these hazards and avoid them.

2) Tire blowouts. Heavy trucks aren't called "18 wheelers" for nothing. Even properly maintained and inflated tires fail on occasion. If a driver has checked all of his 18 tires before his trip, he might not stop for 400 miles or more and an awful lot can happen in 5 or 6 hours of driving. If you are right behind a tractor trailer when it loses a tire, not only will it scare the hell out of you, your car is GOING TO BE HIT by tire debris. A recent Mythbusters episode dealt with the lethality of flying truck tire tread.

3) Sand blasting. I don't know about you, but i kind of like the idea that there is paint on the front of my car. A tractor Trailer produces an enormous amount of turbulence UNDER the vehicle too and any grit or light debris on the road is kicked up and swirls around behind the truck. If the idea of driving inside a sand blasting booth appeals to you, you deserve the damage your paint job will suffer.

This has been mentioned upthread but here is my take: As a driver, it bugs the hell out of me when i am being tailgated. I can't see you and therefore you are yet another hazard i have to contend with. Holders of Commercial Drivers Licenses are held to a higher safety standard than automobile drivers and it is unlikely that an investigating officer will not question the trucker as to why he allowed the tailgater to continue with that behavior.

And a question for OTR drivers...do class 8 and similar trucks have cruise control? This feature is supposed to maximize fuel mileage compared to the foot, on pax cars anyway.

Yes, most these days have CC. With the advent of electronic engine controls in the early 90's, Cruise Control has been standard on most highway trucks since then. They are coupled to wheel speed sensors just like a passenger car so they add fuel on a grade or in a headwind. Also, engines like the Detroit Series 60 have huge torque and wide power bands so when they are mated with the right transmission and rear ends, you can drive over rolling terrain (I 80 across Iowa, for instance) without having to constantly shift up and down.

Ooch, is all I can say.

Hey, I'll do my part for reducing gas consumption. But I can't do it if the trucks are still gonna do 55-60. But if I see one doin 75 or more, absolutely I'll get behind it! I had no idea it would actually make that much of a difference. Thanks for the tip!

They did so in a completely controlled environment and it was still incredibly dangerous.

just the way you wrote it. :eyes:

If I can't see his side view mirrors, I'm too close.

:)

that your car's cooling system is designed to run in clear air (55mph ram effect) and trailing a semi basically slow-cooks your powertrain?

We now have an engine that gets 39% better gas mileage, but must be replaced every fifteen thousand miles, along with a transmission every other engine. Assuming you don't end up wedged under the axles of the trailer.

let's see, you are going to kill yourself and your troubles will be over, but at the same time, you have involved a working man in an accident, potentially caused him to be involved in expensive ligitation to prove his innocence of manslaughter, raised his insurance rates, and all round made it more difficult to put food on the table

how do you look in the mirror every day?

make life difficult for thieves and the elite, not for honest working people who are struggling as it is, jeesus

But the OP conveniently disregarded that fact (see the post upthread about the exploding tire in the same episode).

Manslaughter? Following too closely should never generate a charge of manslaughter the the vehicle in front. You can't control the idiot behind you.

So to get that 39% saving in fuel consumption, you need to be 0.125 seconds behind the back of the truck - less than your reaction time, even if you're expecting the truck to brake. Even the 100 ft back figure means 1.25 seconds - you'd need to be on the ball for your entire journey, with a perfectly maintained car. Is the extra stress worth it?

:shrug:

which is possible, but you have to be paying full attention, the whole time. As also pointed out, your view of the road behind a truck is not good, so you can't anticipate what's going to happen. It's a stressful way to drive.

Most of the time they are so close that we can`t even see them in our mirrors.

first they tell you to "coast" to yellow lights and drive under the speed limit (you know, you will still make it through that stale yellow light, the people behind you won't but fuck them, right?) and now we are told to tailgate fucking semi trucks! Wow!

Good way to end up pancaked against the back of a load. Hopefully the trucker will feel the impact and stop.

Not the backside of an 18-wheeler.

yesterday. I wouldn't advise doing it. If one of my big tires blew, the tailgater wouldn't know what it hit him.

Anybody ever see how much sand and crap trucks kick up as they drive down the road? I'm not going to tailgate a truck to save a few bucks on gas and have to replace my windshield after a rock cracks it or have to have the car repainted from having the paint ruined.