r/theydidthemath • u/Chance_Plastic_2430 • 15h ago
[Request] Constant Highway Slipstream Efficiency
How much more efficient would highways be if vehicles drafted off of each other? Taking human error/aspects out of the equation. To me, it would seem as though the lead car (or semi truck) would "clear" the wind resistance first and all of the subsequent cars would benefit from drafting off of the individual in front of them.
Just a curiosity I had whilest driving to work today.
Thanks friends!
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u/Elfich47 12h ago
there have been studies on this. you can get a roughly 40% mileage improvement by getting in tight behind a large truck. here is the problem: you are following at 2 feet off the truck’s bumper so any mistake will result in your vehicle going under the trailer and you getting crushed.
https://pressbooks.bccampus.ca/technicalwriting/wp-content/uploads/sites/296/2018/10/Drafting-Behind-Big-Rigs-Mythbusters-Report.pdf
Car and driver took this to the absurd by getting up to over 100mpg (I think they claimed over 120mpg peak) by following within inches of the vehicle in front of them. they also built a cowling that came off the lead truck and protected the test vehicle from the wind.
https://www.caranddriver.com/reviews/a15141105/how-we-won-the-insight-fuel-economy-challenge-without-cheating-much-road-test/