View Single Post
Old 07-30-2008, 05:05 PM   #12 (permalink)
aerohead
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 15,861
Thanks: 23,922
Thanked 7,207 Times in 4,640 Posts
freeway coasting

Quote:
Originally Posted by ScottC33 View Post
So let's assume you're the only guy on the freeway, and you have the ability to coast safely from 60 mph all the way down to 20 mph (just as an example), then speed up slowly to 60 mph again (and repeat)? Would that produce the highest mpg, all other things being equal? Or is there some science behind the theory that you should coast only until you hit some predetermined mph before accelerating again?

Obviously, the more you coast (and slower you travel) in neutral, the more fuel you will use to speed up again. What are the current thoughts regarding how far/long you should IDEALLY coast before speeding up again?

I'm trying to figure you whether people coast until hitting 50-55 mph ONLY BECAUSE it's unsafe to go any slower on the freeway, or because there's some other fuel-efficiency issue involved.

This is not an EOC post. All coasting, for purposes of this question, will be done in neutral.

Thanks so much for your input.

Scott
The Chrysler team that used to win the Mobil Economy Run a bunch of times,never coasted,and tried to drive a constant throttle setting,allowing the car to accelerate on downhills,and lose speed on uphill stretches.Simply moving the throttle introduces inefficiency once up to speed.The Coast and Burn technique was introduced in the Shell Mileage Marathon in 1940,it was called "Momentum Driving",it was held on a closed course,not out on public roads.In the "unlimited class",where all the fabulous records were set,the cars were accelerated to 15-mph,engines were shut off,they coasted to 3-mph,and then were bump-started to repeat the process.By allowing your car to decelerate probably introduces the greatest waste you could make.Maintaining a constant speed should yield you the highest mpg.Otherwise,if there is no other traffic,slow down to 35-40 mph.This has been demonstrated to offer the best economy unless your willing to spend the rest of your life on one commute.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote