Drafting and FUel Economy

[RPIpower]

So, I was watching Myth Busters last night and they did this thing with drafting behind a tractor trailer to see if the decrease in wind restriction would improve fuel economy.

Note: I AM IN NO WAY ENCOURAGING DRAFTING. IT IS EXTREMELY DANGEROUS.

Tests were conducted at a highway speed of 55mph.

-At 7 car lengths, the test vehicle received a 20% decrease in drag.

-10ft behind equals 60% decrease in drag

-6ft equals 80% decrease

-2ft equals 90% decrease

At 20% decrease, they got an 11% increase in fuel economy. The car started at 30mpg and at 80% they were getting 44mpg! lol. The only reason the 2ft test gave them less mpg was because they were on and off the throttle to maintain the 2ft distance.

OK, so I do the stupid thing and followed a truck this morning. I hit the reset button on the fuel econ and wanted to see if it worked for me. I followed the truck, within a safe distance (probably 5 car lengths) and did see the ecu recalcute the fuel econ and addded +3mph.

[xmicro_Redline]

Originally Posted by RPIpower

So, I was watching Myth Busters last night and they did this thing with drafting behind a tractor trailer to see if the decrease in wind restriction would improve fuel economy.

Note: I AM IN NO WAY ENCOURAGING DRAFTING. IT IS EXTREMELY DANGEROUS.

Tests were conducted at a highway speed of 55mph.

-At 7 car lengths, the test vehicle received a 20% decrease in drag.

-10ft behind equals 60% decrease in drag

-6ft equals 80% decrease

-2ft equals 90% decrease

At 20% decrease, they got an 11% increase in fuel economy. The car started at 30mpg and at 80% they were getting 44mpg! lol. The only reason the 2ft test gave them less mpg was because they were on and off the throttle to maintain the 2ft distance.

OK, so I do the stupid thing and followed a truck this morning. I hit the reset button on the fuel econ and wanted to see if it worked for me. I followed the truck, within a safe distance (probably 5 car lengths) and did see the ecu recalcute the fuel econ and addded +3mph.

I guess I save gas every night in that NYC Bumper to Bumper 30MPH traffic!

Cool facts, gotta love the Myth Busters!

[Chemist]

CAVEAT: DO NOT TRY THIS AT HOME!

Back in grad school, I rode bicycles competitively. One group I trained with used to ride on a bypass west of town. One day, a semi was coming down the on ramp to the bypass just as I was spooling up for a sprint, I was doing about 25 mph when he pulled onto the road, and I caught his draft. Suddenly I was doing 35, then 45, then 50 mph. It was not until I thought about the fact that I was doing this speed while riding 120 psi tires with a total contact patch of less than 2 square inches that I got scared and backed off. The air behind these big trucks is very "clean" indeed (i.e. nonturbulent).

[Skip]

Eloy I had an old AMC Hornet that I used to draft trucks going back and forth to school over 30 miles away. I would come up behind them and blink my lights and hide in that wake. If something happened they would click there lights on and I would back off. It saved me a lot of gas money.. Skip...

[Scottoj]

I too used to race bicycles competativly, and woudl do this on a semi normal occasion, and many times behind someone driving my car, its called motor pacing, and its awesome. Although, i kinda have to disagree with their reason why fuel economy droped when they went within 6 in. I believe it is more from the air coming from below the truck. When riding my bike, i could definatly tell a difference when getting behind a truck, when you got too close it did get harder. But with a lower vehicle, like my volvo station wagon, the closer the better. And yes i would get within inches of the bumper, even taped it a few times when going 45+ mph (talk about scary).

Either way, economy or not, i choose not to do this, not for the danger factor or getting in a accident, but more cause trucks throw up rocks pretty regularly, and well, i dont mind it hitting me while on my bike, but i dont want it to land a nice ding in my paint, or crack in my windshield. So i stay as far away from Big Wheels as possible.

[Sw0l3n4t0r]

lol i would be more afraid of rock flying up hitting me in face causing me wreck and getting ran over

[Aquaholic]

I drove a Jeep Wrangler in college, my commute was 25mi one way. I installed a CB and would ask permission to draft - that Jeep got great mileage behind those trucks - ahhh...memories.

[Antonio]

I saw that same episode of the Mythbusters. DVR every single one. Of course, all us idiots see that and say...."i gotta try that!" even though we all know the dangers and how dumb it is, heh heh.

I just wanna learn new ways of how to blow stuff up in the same of TV Science.

[KSTHSKY]

If you really want to "feel" the effect of drafting on drag, ride a bicycle in a paceline. You learn a lot when YOU are the engine.

[Im Fastr]

Originally Posted by RPIpower

So, I was watching Myth Busters last night and they did this thing with drafting behind a tractor trailer to see if the decrease in wind restriction would improve fuel economy.

Note: I AM IN NO WAY ENCOURAGING DRAFTING. IT IS EXTREMELY DANGEROUS.

Tests were conducted at a highway speed of 55mph.

-At 7 car lengths, the test vehicle received a 20% decrease in drag.

-10ft behind equals 60% decrease in drag

-6ft equals 80% decrease

-2ft equals 90% decrease

At 20% decrease, they got an 11% increase in fuel economy. The car started at 30mpg and at 80% they were getting 44mpg! lol. The only reason the 2ft test gave them less mpg was because they were on and off the throttle to maintain the 2ft distance.

OK, so I do the stupid thing and followed a truck this morning. I hit the reset button on the fuel econ and wanted to see if it worked for me. I followed the truck, within a safe distance (probably 5 car lengths) and did see the ecu recalcute the fuel econ and addded +3mph.

Saw the same episode a few weeks ago... love that show.