Hypermiling - is anyone trying it?

[StorminN]

Is anyone trying it? The basic stuff makes sense... drive slower, inflate your tires to the max rating, remove unused belts (like AC belts here)...

But some of the stuff is counter-intuitive to me... for instance, I assumed driving in a higher gear (lower rpms) would use less gas... but if you read the BSFC stuff, it says medium to high rpm's and wide open throttle is actually more efficient!?! This is a big part of how the Prius and Insight hybrids get better mpg's.

Interesting:
General Introduction to Hypermiling

Really interesting (I'm going to wire this up):
DIY Fuel Rate Meter

Really really interesting:
Brake Specific Fuel Consumption

My 1991 Subaru wagon (1.8L engine, 5-speed) is currently averaging 26mpg (last five tanks)... I'm going to try some of this out and see if it makes a difference...

-Norm.

[Warbird]

Driving slower may help but I've found that what makes the largest difference is in how you accelerate.  I was one of those guys who would mash the pedal down to get up to the speed limit as fast as possible.  This consumes a *lot* more fuel than if you take yer time getting up to speed.

[Greg]

Didn't read your links, but...

It works. I've done it.

My subaru has rated mileage of 20/27, but I can easily average over 30 mpg in mixed suburban/highway driving conditions.

By carefully driving I'd say anyone could increase their mileage 25%. Single biggest fuel waster, as someone already said, is jackrabbit starts. Also, I was surprised to find I'm better off with AC on the windows shut then the windows open - due to air resistance, esp. at highway speeds.

The downsides/reality of course are significant:

1) if you are in a rush to get anywhere, forget it
2) get used to everyone riding your bumper, now that you drive like a granny..
3) don't get complacent/fall asleep with that cruise control
4) its not a good way to impress your date!

 
Greg

[PC-Urban-Sawyer]

I hypermiled once, back in the early 70's...

I was coming back from Reno, Nevada going to Vallejo, California. I'd lost all my cash and didn't have a credit card. I didnt' have enough gas in the little Austin Healey Sprite to drive all the way back to the Navy base. Once I made it past the peak of the Sierras on Interstate 80, I put the transmission in neutral and turned off the engine. Must have coasted at least fifty miles deadstick. Got a little scary a few times, that's the fastest that little car ever went, with or without power...

Made it almost 200 hundred miles on less than a half tank of gas... I probably averaged about seventy mpg on that trip...

[sawguy21]

  Did the car need new brakes shortly after that? I did something similar one night trying to nurse a Ford pickup to a gas station but it was a hairy ride down the mountain with no compression braking. I needed the engine running for the p/s and p/b.
I am certainly more conscious of my driving habits with the current price of gas. I slow down and drop out of o/d on the hills and smooth acceleration at the lights. We are looking at a small travel trailer for the summer but motels might be a better option.

[StorminN]

Driving slower may help but I've found that what makes the largest difference is in how you accelerate.  I was one of those guys who would mash the pedal down to get up to the speed limit as fast as possible.  This consumes a *lot* more fuel than if you take yer time getting up to speed.

Warbird, this is exactly what I don't understand... granted I read it only once, late last night... but the gist of what I got from the BSFC article is that they're saying you're better off driving with the throttle wide open, shifting sooner... the engine runs more efficiently at, say 2,000 rpm's than it does at 700 or 4,000...

I've got a Fluke multimeter with % duty cycle, I'm going to tap my injector wire and see what it reads like in my "normal" driving style...

-Norm.

[Bibbyman]

From all the trips we’ve made with our 3500 Dodge in the past year,  I’ve learned that I get better gas mileage by not using the cruise control – especially when loaded or in rolling hills, etc. 

The Dodge has an automatic transmission with overdrive and some kind of lock in feature.   As soon as there is much need for torque, the lock kicks out and then soon after the overdrive kicks out.  Loaded on the toughest grades, it will kick down and gear and the engine hits about 4,000 RPMs.   But if I don’t used the cruise control and kind of let it build up some speed going down a grade,  I can generally feather it back on the next rolling hill so it don’t change gears nearly as often.   

[breederman]

I gain about 10% on my daily rounds by watching my starts and stops, holding, speed down,etc.  If I get busy and in a hurry mileage will drop sharply.  I check my mileage every fill up{1 1/2 to 2 days}  it helps keep me focused.

[Left Coast Chris]

Bibby,  our 2007 1500 Dodge 4X4 has a tow/haul button on the end of the shift lever.  That makes it not kick down to the lower gear as easy but also seems to keep the rpms in the 2500 range when towing in hilly terrain.  It will let it kick into overdrive to about 1500 rpm if on a complete flat and the load is not too heavy.   I never tried the cruise control when towing or in hilly terrain.  I love the transmission though.   You usually can't even tell it is shifting it is so smooth.

[Handy Andy]

  I have an old Toyota pu that I use for running around, just use the heavier trucks when I need to haul or pull a trailer.  Have found that I can coast quite a bit if I work at it.  Yeah, even the grannys get sore when you coast the last 1/2 mile before you turn a corner.  But it saves gas.  Funny how now they don't pass like drivers used to.  I can coast the last mile home, and very seldom anybody passes. 

[fencerowphil (Phil L.)]

The techniques do work, but it does increase my travel time
a lot.  Seldom do I find traffic conditions which allow me to do it.
I travel a lot of two lanes and it seems like all the chalk and log
haulers on my bumper are runnin' empty and haulin' buggy!

[Toolman]

I agree with Bibby,

I have an F-250 Powerstroke diesel and get lousy mileage using criuse control on hilly terrain. I drive 28 miles to work and averaged 19 mpg with cruise using scan guage. Without cruise on same route I'll easily average 24mpg.

[Ron Scott]

Cruise control isn't efficient on hilly terrain, only use it on flat running.

[Fla._Deadheader]

  Ed and I used to watch the Boost gauge, on the Dodge Cummins. We ALWAYS got better mileage than using the Cruise control.

[Ironwood]

Does coasting down to my storage area on the forklift count? I shut her off and cruise down then power up for the trip back "up" the 3% grade.   Those old Continental 4 cylinders SUCK the gas. They used them in just about everything.
 
 Ironwood

[StorminN]

Ironwood,

I would say that counts!

-Norm.

[StorminN]

Update -

After trying some of these methods (mostly the driving-in-a-higher-gear, more open throttle method) and removing the roof rack (less drag) from my Subaru wagon, for my last tank I got 27.2 mpg, as opposed to 25.0 mpg, which was my average for the five tanks before then. This is an improvement of 8.8%. Granted, this is just one tank full, but the results are promising!

Now it's time to give the old car a tune-up...

-Norm.

[happyj]

i have been trying this for the past couple of months. I keep my foot out of it, coast downhills, start off slow. I have always shifted pretty low so that has not changed but, i get 44mpg up from 40mpg. I can not convince myself to slow down for the 14 miles of freeway (65) i have a mental block with it. I drive 38 miles each way and only use the car for commuting. I have a 91 corrola that i want to do something on the electric car front. I want a sawmill more though at this moment.

[StorminN]

I have always shifted pretty low so that has not changed but, i get 44mpg up from 40mpg.

I say 10% is nothing to shake a stick at!

-Norm.

[fencerowphil (Phil L.)]

I have always wondered why someone had not come out with what I call
"soft cruise control."  In effect, it would do hyper-miling for you on mildly
hilly terrain.  The amount you would  bog down would be a user-set-variable,
and would be matched by a down-hill gain in speed.

Seems like it would save about 6-8% over using standard cruise on hills.