# Riding in truck's wakes for gas mileage **URL:** \ **Category:** Factual Questions\ **Created:** [October 26, 2004, 5:39pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267 "2004-10-26T17:39:15Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Doparama](https://avatars.discourse-cdn.com/v4/letter/d/5e9695/32.png) [@Doparama](https://boards.straightdope.com/u/Doparama)\ **Post date:** [October 26, 2004, 5:39pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/1 "2004-10-26T17:39:15Z")
As gas prices continue to climb I feel the need to get every last mile out of each gallon of gas. I keep my tires properly inflated, I try to avoid rapid acceleration, and I try to keep my car at an acceptably moderate speed. Now I am tempted by the wakes of trucks… Anyone know just how close you need to be to the back of a truck to benefit from the reduced air resistance? Any idea, on average, how many MPGs you could expect to gain? (I usually get about 31 or 32 MPG.) Is it foolish to ride around this way when you might hit debris that the truck didn’t mind driving over? :smack: ---
**Author:** ![Chairman\_Pow](https://avatars.discourse-cdn.com/v4/letter/c/838e76/32.png) [@Chairman\_Pow](https://boards.straightdope.com/u/Chairman_Pow)\ **Post date:** [October 26, 2004, 5:47pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/2 "2004-10-26T17:47:21Z")
Back when I was a foolish 16 year-old who just got his license, I tried drafting behind a truck. I recall I had to get really close (as in so close, I couldn’t see his mirrors and he certainly couldn’t see me) and then I noticed the tachometer ease up a little. He didn’t like me back there and flashed his brake lights. I got out of there and never tried it again. From my completely unscientific sample, I recommend that you don’t ever try this because it’s a safety hazard. ---
**Author:** ![Doparama](https://avatars.discourse-cdn.com/v4/letter/d/5e9695/32.png) [@Doparama](https://boards.straightdope.com/u/Doparama)\ **Post date:** [October 26, 2004, 6:03pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/3 "2004-10-26T18:03:08Z")
Seems to me there ought to be some medium between hazardously close and safely close but still benefitting from the draft. No? ---
**Author:** ![Triskadecamus](https://avatars.discourse-cdn.com/v4/letter/t/b19c9b/32.png) [@Triskadecamus](https://boards.straightdope.com/u/Triskadecamus)\ **Post date:** [October 26, 2004, 6:13pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/4 "2004-10-26T18:13:48Z")
At six inches from his bumper, you get a real boost in mileage. At six feet, you get about half that. At six car lengths, you loose as much to turbulence as you gain from draft. Six and a half car lengths is the minimum safe following distance if you are obeying the speed limit, and so is he. How high is the price of gas, where you live? High enough to hang around six inches from a tractor trailer? I doubt it. ## Tris “These things that are pleasin’ you can hurt you somehow.” ~ Don Henley & Glenn Frey ~ ---
**Author:** ![silk1976](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@silk1976](https://boards.straightdope.com/u/silk1976)\ **Post date:** [October 26, 2004, 6:42pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/5 "2004-10-26T18:42:26Z")
I dont have anything to add regarding whether its worth it to ride the bumper of a truck to improve gas mileage, but I definately view it differently - I’ll pay a few more cents in gas per mile to drastically reduce the risk of being in an accident. Accidents cost a lot, gas is still relatively cheap. Add in the fact that an accident with a truck can easily total your car (and likely squish you in the process), and falling back a few car length seems like a real good investment 🆒 It amazes me how often people (I’ve done it myself in the past) lose sight of the big picture just for the sake of saving a relatively small amount of money - like when people drive 10 extra miles to save $0.05 off a gallon of gas. ---
**Author:** ![Doparama](https://avatars.discourse-cdn.com/v4/letter/d/5e9695/32.png) [@Doparama](https://boards.straightdope.com/u/Doparama)\ **Post date:** [October 26, 2004, 6:54pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/6 "2004-10-26T18:54:16Z")
> [@Triskadecamus](#): > > At six inches from his bumper, you get a real boost in mileage. At six feet, you get about half that. At six car lengths, you loose as much to turbulence as you gain from draft. Six and a half car lengths is the minimum safe following distance if you are obeying the speed limit, and so is he. OK, I’m thinking I’ll just stick to proper tire pressure & reasonable speeds, but I’m curious - where did you come up with these numbers? ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [October 26, 2004, 7:18pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/7 "2004-10-26T19:18:29Z")
> [@Doparama](#): > > OK, I’m thinking I’ll just stick to proper tire pressure & reasonable speeds, but I’m curious - where did you come up with these numbers? Don’t forget the [Safe Stopping Distance](http://www.plasticsurgery4u.com/richmond_virginia/drivesafe.html) whether behind another auto or TRUCK! ---
**Author:** ![Doparama](https://avatars.discourse-cdn.com/v4/letter/d/5e9695/32.png) [@Doparama](https://boards.straightdope.com/u/Doparama)\ **Post date:** [October 26, 2004, 7:34pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/8 "2004-10-26T19:34:19Z")
> [@spingears](#): > > Don’t forget the [Safe Stopping Distance](http://www.plasticsurgery4u.com/richmond_virginia/drivesafe.html) whether behind another auto or TRUCK! ENOUGH ALREADY with you mamby-pamby drivers!!! With the indulgence of the moderators I would like to take a hypothetical tack on this question. **Lets assume that the driver is an idiot with no regard for safety whatsoever.** What kind of “window” behind a truck is there for drafting? How much of an improvement would the foolish driver get in his mileage? ---
**Author:** ![DeVena](https://avatars.discourse-cdn.com/v4/letter/d/dec6dc/32.png) [@DeVena](https://boards.straightdope.com/u/DeVena)\ **Post date:** [October 26, 2004, 7:34pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/9 "2004-10-26T19:34:57Z")
Please don’t try this. Back in my wayward youth, I was drafting behind a heavy loaded semi during the wee small hours of the morning. The truck hit something and proceeded to sling it back onto my tiny VW Rabbit. To this day, I don’t know what he hit. It must have been a small deer. At least I hope it was. Broke my windshield and covered my car in blood. And no, he didn’t stop and neither did I. If the truck has a problem, you would be far to close to do anything but impact. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [October 26, 2004, 8:08pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/10 "2004-10-26T20:08:15Z")
> [@Doparama](#): > > ENOUGH ALREADY with you mamby-pamby drivers!!! > What kind of “window” behind a truck is there for drafting? How much of an improvement would the foolish driver get in his mileage? ENOUGH of the STUPIDY! “The game isn’t worth the chase.” Translation FYI “not enough gain to risk life and limb.” Forget a smallest window and **DRIVE SMARTLY**! ---
**Author:** ![Doparama](https://avatars.discourse-cdn.com/v4/letter/d/5e9695/32.png) [@Doparama](https://boards.straightdope.com/u/Doparama)\ **Post date:** [October 26, 2004, 8:16pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/11 "2004-10-26T20:16:38Z")
> [@spingears](#): > > ENOUGH of the STUPIDY! > “The game isn’t worth the chase.” Translation FYI “not enough gain to risk life and limb.” > Forget a smallest window and **DRIVE SMARTLY**! Ach, spingears!!! I believe I revised the question to a hypothetical “what if?” Work with me here. Perhaps, for the sake of verisimilitude, we should place our hypothetical truck and idiot driver in NEW JERSEY!!! Any takers? ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [October 26, 2004, 8:35pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/12 "2004-10-26T20:35:50Z")
> [@Doparama](#): > > Ach, spingears!!! I believe I revised the question to a hypothetical “what if?” Work with me here.Perhaps, for the sake of verisimilitude, we should place our hypothetical truck and idiot driver in NEW JERSEY!!!Any takers? OK You will now need to know the specific truck, auto, speed, separation, air temperatue, barometiric pressue, humidity, wind direction, wind speed, and any other factors that may affect the result sought. A willing physicist/engineer to do the necessary esoteric calculations would be very helpful! ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [October 26, 2004, 8:38pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/13 "2004-10-26T20:38:18Z")
> [@spingears](#): > > OK You will now need to know the specific truck, auto, speed, separation, air temperatue, barometiric pressue, humidity, wind direction, wind speed, and any other factors that may affect the result sought. > A willing physicist/engineer to do the necessary esoteric calculations would be very helpful! OOPS I forgot to mention road surface, tire conditions, and direction of travel. :smack: ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [October 26, 2004, 8:40pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/14 "2004-10-26T20:40:42Z")
> [@Doparama](#): > > I keep my tires properly inflated[.] Good step. > [@](#): > > I try to avoid rapid acceleration[.] Good step. But… did you know that accellerating too slowly wastes a lot of gas, too? It can also be dangerous to other drivers, as they’re going to have an aweful urge to get around your slow ass. > [@](#): > > …and I try to keep my car at an acceptably moderate speed. Probably the best thing you can possibly do. Uh, you _do_ stay out of the left lane, right? > [@](#): > > (I usually get about 31 or 32 MPG.) _What?!?_ Why the hell are we offering you any advice in the first place? This is incredible mileage unless it’s a 3-cylinder Geo. Hell, people get tired of _my_ complaining about 22mpg, and my pedal is almost always to the floor, and the tire pressure is only guaranteed right every 5000 miles (oil change time, I assume they check the pressure). Go to hell you commie bastard! (FWIW, those last comments are lame attempt at humor, and I’m not doing anything that should get me banned or booted to The Pit. :)) ---
**Author:** ![Chairman\_Pow](https://avatars.discourse-cdn.com/v4/letter/c/838e76/32.png) [@Chairman\_Pow](https://boards.straightdope.com/u/Chairman_Pow)\ **Post date:** [October 26, 2004, 8:47pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/15 "2004-10-26T20:47:44Z")
> [@Balthisar](#): > > I’m not doing anything that should get me banned or booted to The Pit. :)) Yes you are. ---
**Author:** ![Stan\_Doubt](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@Stan\_Doubt](https://boards.straightdope.com/u/Stan_Doubt)\ **Post date:** [October 26, 2004, 8:49pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/16 "2004-10-26T20:49:02Z")
About 3 years ago, Car and Driver ran a story on a publicity stunt in which the editors of several motoring magazines were invited to drive new Honda Insights (recently introduced) from point A to point B whilst trying to extract the highest fuel efficiency from the vehicle. The crafty CD editors rigged a Ford Expedition with wind blocking flaps and drove the Insight within inches of its rear bumper for as much of the trip as possible. The Ford’s driver communicated his intentions to turn, slow, stop, etc. with hand gestures. They won the contest hands down, but I do not recall the exact mpg figure they achieved. ---
**Author:** ![Doparama](https://avatars.discourse-cdn.com/v4/letter/d/5e9695/32.png) [@Doparama](https://boards.straightdope.com/u/Doparama)\ **Post date:** [October 26, 2004, 9:02pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/17 "2004-10-26T21:02:43Z")
> [@Balthisar](#): > > Good step. But… did you know that accellerating too slowly wastes a lot of gas, too? It can also be dangerous to other drivers, as they’re going to have an aweful urge to get around your slow ass. I said I _avoid_ rapid acceleration. I DO accelerate - I just don’t floor it. > [@Balthisar](#): > > Probably the best thing you can possibly do. Uh, you _do_ stay out of the left lane, right? yes dad… > [@Balthisar](#): > > Go to hell you commie bastard! THAT’S THE SPIRIT BALTHISAR!!! ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [October 26, 2004, 9:26pm UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/18 "2004-10-26T21:26:44Z")
I once drafted a gasoline truck on I-5 :eek: while a stong wind (25 mph) was blowing in the same direction in CA’s Cental Valley. Two observations: ``` 1) You don't have to draft as close with that kind of wind (about two car lengths) 2) The car will start over heating in about two minutes (it was in the high 70s that day). ``` I still draft but only using a bicycle… ---
**Author:** ![Muffin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muffin/32/4341_2.png) [@Muffin](https://boards.straightdope.com/u/Muffin)\ **Post date:** [October 27, 2004, 1:57am UTC](https://boards.straightdope.com/t/riding-in-trucks-wakes-for-gas-mileage/271267/19 "2004-10-27T01:57:06Z")
I just wish that trucks on the top of Superior run would stop drafting me.