Auto FE - It's all about driving style
 

OK. I have been spending a lot of time trying to figure out how to boost the mpg in my 2000 Honda Civic Coupe EX w/ auto transmission for the past month. My whole goal is to save money so spending money on major mods is just not an option.

Outside of boosting the PSI in my tires from 35 to 45, I haven't changed anything to the car in the last month. So I have been focusing a lot on what options I have on driving style. Obviously with an auto transmission, coasting with the engine off just isn't an option. So I have been playing around with my techniques and thought I would share with the group what I have learned so far.

This is for the newbies to this site. I am sure the veterans are all aware of what I am about to list. Most of these relate to highway driving w/ 65 mph speed limits.

1) Reduce Rolling resistance - bump up the PSI in the tires to help reduce rolling resistance and keep an eye on the pressure in each tire. I have two tires that seem to leak air very, very slowly when pumped up to 45 psi.

2) Downgrade Slope Multiplier w/ Neutral Coast - Accelerate quickly down the downhill slope to 5 or 7 mph over the speed limit prior to going up a hill. This uses gravity as a multiplier to boost your mph acceleration with less gas. You can then wait until you have reached the steepest grade uphill and shift to neutral and coast until you are about 5 mph under the speed limit and then add the gas. Be sure to maintain speed with the gas going up hill and not try to accelerate uphill. The less gas you use uphill, the better your FE.

3) Safe Drafting- Never go down the road at highway speeds without trying to be behind someone to catch a bit of draft advantage. Even if it is a pickup truck or minivan, there are advantages to this. Minivans are good because you can often see straight through the minivan windows to see the brake lights of the vehicle in front of it. This gives you more time to brake if traffic slows down quickly. If you can get behind a semi w/ box trailer, your drafting will be even better. I accelerate up close behind the semi (within 20 ft or so) and then shift to neutral and coast for a while. This helps a bunch but this opportunity isn't always available. It also removes the ability to coast uphills as mentioned in #2 above.

4) Side Roads / Access Roads - Most of the time, these roads are much less traveled. If there is a way to drive on these roads at about 10 mph less than the highway or regular route you take, that decrease in speed will help with FE. The trick is avoiding or timing stop lights. That all comes from knowing your route really well and deciding if it really helps or not. With these open stretches with less traffic, you can also add other techniques such as accelerating downhill and neutral coasting up hill. Drafting won't be as much of a benefit at slower speeds.

This is all I have so far but thought I would share with the group. It is so hard to find things that can be used for vehicles with auto transmision that I really thought I should share with the group. These techniques are working for me as I have been able to boost my mpg from 33 to 40 in the last 30 days.

If you have other driving techniques that also help, by all means, add them to this thread. I need more ideas.

I also suggest getting a scangauge. It'll let you see, in real time, what helps and how much it helps. It really helps you optimize your driving style. In a year, it's saved me enough to pay for itself, and now enough to buy another if I wanted.

so what speed do you reccomend... i just got in to a civic from a crv and i am seeing that the fe speed is not what it was for my crv...

If it's an automatic, whatever speed will keep it in top gear, and just a little above that. Probably 45-50 mph.

Manual - the best speed is slower. ;) Keep the rpms down and use moderate throttle.

I agree with PaleMelanesian. It does seem that 45 - 50 seems to be about right for my 2000 Civic. Even if you don't have a ScanGauge (which I don't), you can keep an eye on your RPM gauge and pay attention to when your auto trans shifts gears. With practice, you can learn how to keep it in the lowest range of your top gear for best efficiency.

One correction to my original post, I have since abandoned trying to draft behind trucks, etc. I usually have to run at a faster speed to stay in the draft and it is way too much work to be in that zone and be ready to brake if needed. I have found it is better to run at 63 mph in a 65 and let people fly by me instead. I get much better gas mileage that way and run at a little lower RPM too.

By the way, take a look at my garage log to see the improvements from perfecting these driving practices over the last several months.

Hey, Scott! That's a nice bump in your gaslog chart! Keep it up!

Pale,

Don't let that last log entry fool you! That was only 3 days of driving over the weekend with perfect driving conditions to hit over 49 mpg.

It did wake me up to the potential of the car though and the impact of driving style on fuel efficiency. I do think that with my daily commute FE will end up around 39 mpg as I continue to put into practice what I am learning.

When i first start my old 94 intrepid i put it in gear and just let to go without stepping on the gas pedal. The read out on the gauge that came with the car for mpg starts climbing up to 14 to 18 mpg as i gain speed still not stepping on the gas. It is only going 15 mph but at 18 mpg it is very efficient until warm up and then i start using the gas very gently. This may help you when you start to go in your car.

1cheap1,

Thanks. That is interesting. I live on a deadend road so I have a 1/2 mile to go as fast or as slow as I want with no traffic problems. I will hav to try this. It may not be as much of an issue in the warmer summer months as the car will warm up faster or even start out somewhat warm.

Hi Scott - good going.
I've been hypermiling my auto-tranny car for a bit more than a year now and my bag of tricks is just about identical to yours. I drive mostly highway too.

I also found that drafting is good for FE but I just don't like following that fast and that close. Occasionally I'll find something I can follow at 55-60 mph but not very often.

I've gotten used to driving slower on roads posted 65 mph. I find I'm able to drive 50-55 if that's what I want to do. I do have a big 'MPG' sticker on my back window so maybe that helps people understand why I'm not going 70.

My tires are labeled 44 psi but I have them at about 53. No, I'm not afraid of a blowout. Side topic: with a commute of 60 miles each way I carry a full size spare. If a tire does quit on me for whatever reason I want a fully capable one to complete my trip. I like donuts to eat, that's all.

Carpooling really improves fuel economy. Hurts your mpg just a bit but can double or triple your fuel economy!

Some other techniques I found on today's long 500-mile drive (check my gaslog for the big jump upwards)

When going downhill, do engine-on coasting. However, if going downhill over the speed limit, or there are sharp bends coming up, go back to drive, and try to get it to go into fuel-cut mode (done on my car be putting it in gear, accelerating slightly to engage lockup, then letting go (this only works when I have disconnected the lock-up control lead).

If you have lock-up that disengages at 80km/h (50mph), it may be that your most efficient speed is 51mph, but there is another efficiency peak when the torque convertor is slipping. On my car that was at about 35mph. So, I would do up-hill stretches at high-throttle load (just before enrichment), but once the car slowed down too much, I would go into neutral until about 35mph, then back into gear and would continue the up-hill at 35mph.

Finally, engine-on pulse-and-glide is great for mild downhill stretches where the car slows down but the 100-80km/h (62-50mph) stretch is prolonged by the slight downhill grade. (note you need to go into neutral when on the glide for this to work).

Keep it in neutral
 

One more - Neutral at stoplights. Many people with automatics forget this one. Note my MPG % above EPA and you'll see it does help.

Neutral
 

Use neutral as much as possable, stop-lights, down hills and prior to stops. Use the big gear. 28 city 35 highway 99 passat epa 21/31

When you're not interested in reducing speed, neutral makes sense because it won't drag your speed down. When you want to reduce speed, use enough engine braking to trigger DFCO (if your car does DFCO).

It's commonly thought that higher RPM == more fuel usage, but does it if you're not stepping on the gas and the road is turning the engine (but, for whatever reason, not in DFCO)? Would the engine need to inject the same volume of fuel more often for more RPM, or it can it inject less fuel? Can anyone answer that definitively? I will when I eventually get a ScanGauge.

On my auto, idle is 750rpm, and fuel cutoff works above 2000rpm. Therefore, if I am driving with the engine at 1800rpm, it makes sense to pulse, and then glide in idle. Otherwise it injects lots of fuel even if it could have been in cut-off mode.

More modern cars have much better cut-off modes, however. Or at least they should! (The Toyota Avensis D4-D (diesel) has cutoff at any speed above idle :)

Wow, I must admit, some of this is hard to follow. Can anyone tell me what is the safest way to come out of neutral when I need to speed up?

What I have been doing is going into neutral up even the smallest road hills, then mildly accelerating downhill till I hit level or get done accelerating, then putting the car into neutral. My rpms are always at 9-1.1k when moving in neutral(750 idling).

So if I say... coast in neutral all the way over a hill, then mildly accelerate down, cut it to neutral then coast out till I am going about 5-10 mph less than the speed limit, should I rev my engine a little before putting my trans back into drive? I have recently started doing this, and it is the smoothest way to go back into drive while moving. Help?

I'm not sure about your Volvo, but in every GM I've ever owned (and probably some Fords I drove a lot) I never had to think about it, I just go from N to D without touching the gas pedal until D is fully engaged.

I run aftermarket rims and tires, have an auto tranny and a turbocharger. I do a couple things to help.

1. Reinstalled boost guage. I used to use it for performance, now I use it to stay in vacuum and make sure Im not in boost.

2. Feather the throttle to keep it under 2200rpms or so. I have "autostick" but I find if the RPMs get too high, I let off the throttle a little bit to get the transmission to shift then I speed up again. I only do this through the first 3 gears - 4th is OD for me and a weak point for the 41TE.

3. Speed up slowly, maintain speed limit or below. Duh

4. Try not to use either pedal. You shouldnt need to brake hard or speed up hard if youre in tune with traffic.

I do pretty well all things considering. We also have a 2008 Yaris that gets 40mpg with barely trying so thats the mpg car. Picked it up for 11k OTD with 1,400 barely used miles from a Chrysler dealership. Bare bones with 5 speed and the convenience package.

On my Odyssey, the transmission jolts a bit when going back into drive above about 40mph. In that case, I blip the throttle to about 2000 rpm to rev-match first. A little high seems to be smoother than a little low.

is it bad to turn off you car when your able to glide a good distance? because I do that. I have a 93 saturn sc2 auto. I have got several places on my usual routes that i can put my car into neutral, turn the car off and glide, you loose power steering, but 30+ you don't need it, and power brakes after a few hits. There is one area that i think i glide for nearly a quarter mile before the stop sign comes. i have to look at my tripmeter next time i go there. i only do this if i'm going to be coming to a complete stop, if something happens, suppose the light turns green before my spot, i just turn on the engine, wait for it to stablize and tap the accelerator to get the rpms up if need be, put it into drive and go.

g2k556, welcome to the site.

Check your car's manual for flat-towing ability. If it says you can tow it with all four wheels down then it's probably okay to EOC. If not then you are risking your transmission.

Good advice. I think those saturns are fine, though. I've seen them behind RV's.

yep, i just checked the owners manual and they are good for towing :thumbup:

One more thing. I tested this morning, and my Honda does fuel cut down to 1200 rpm.

I am impressed!
 

Guys - I really like how this thread is continuing. I was afraid it would die on the vine when I made the original post since it seemed like very few people who cared about FE had auto trans vehicles.

I have to say that my continued work on driving style (and lately and more importantly driving route) has really increased my MPG even further. I hit 44 mpg this morning when I filled up. Not bad since the newly adjusted EPA estimate puts it at 28 or 29 combined. That's 52% above the gov't estimate. This is really important since I am trending towards putting 23,000 miles on my car this year with my daily commute, etc. (right now, 1894 miles a month).

I still don't have a ScanGauge but am developing a pretty good feel for what works and what doesn't. I am sure I am still missing out on some techniques that might bump me up another 1 or 2 mpg but can't convince myself to drop the $160 or so on a ScanGauge unit.

Thanks to everyone that has participated on this thread so far. A lot of you guys are a LOT more technically minded than I am and I haven't completely followed everything said but I am learning.

Thanks again!

Scott - all good stuff. That's about all I'm able to do in my Mustang, as with a carbureted car like my Mustang, there's no ScanGauge, no DFCO, and little if any benefit to neutral at stoplights. Indeed...I think neutral for me would be worse as the primaries are open to the same position, but in N it's revving 200rpm higher than in gear. I've inflated my tires to sidewall max (35psi) but won't go any further as they're pushing 14 years of age and one has a plug in it. Using the downhills to build momentum for uphills is an important one here, as we have a landscape dotted with rolling hills, and it usually helps to the tune of 5-7%.

So far, the biggest help to me has actually been installing a fan clutch (these cars didn't come stock with one unless it was a/c equipped, which mine is not), much more than even my right foot. Like the '68 hardtop I had in high school, the car has so much torque for its weight that your acceleratory style has little effect on the mileage - I've noticed less than 1mpg difference in both cars between my granny driving and harder driving. The fan clutch has a double whammy effect in that the car is able to run ~15* warmer and the motor isn't slinging a 5-bladed fan around at 1.8x engine speed everywhere I go. Informal observations about having my top up vs. down hasn't revealed the expected gain from having the top up, either.

jcp123,

I hear ya. Those older Mustangs were built well but not for mpg fuel efficiency. You could do a lot of things to make your Mustang get better gas mileage but then it wouldn't feel or drive like a Mustang any more. I think the best bet for you is to ride your 1100 motorcycle as much as possible. You could take it easy from a riding style with the bike and still get around 40 mpg or so. Plus, you would continue to get the surround sound sensory experience that can be only had with a bike or a convertable.

I know it is tough to find right now, but if you drive quite a bit, it might be worth trying to pick up a mid-90's subcompact import that can get better gas mileage and keep the 'stang and bike around for those enjoyable rides.

Hmm, I should update that sig. The bike's been gone for about 5 months now, but it was really easy on fuel - my commutes actually averaged around 47mpg, highway trips were pretty consistent at 52-53mpg! Fantastic for an 1100cc, but the dated design of the Shadows really comes through. Right now I'm saving up for a Harley Sportster to build a bobber bike out of as my fuelsaver - the big, heavy flywheel allows these torque monsters to cruise at low RPM's with bigger throttle inputs, reducing pumping losses and yielding pretty impressive mileage. My Dad and I are also working to get a '61 Mercedes 190b roadworthy for a family grocery getter. With a 1.9l SOHC four and a four-on-the-tree, it should be pretty decent in the mileage department.

After I'm done with school and move out, space permitting, I'd love to get a late '65 Mustang with the 200ci I6/3-speed stick combo - they're capable of touching 30mpg on the highway weighing in at only around ~2600lbs. The other option would be a '58 Chevy Biscayne 2-door post, Chevy's base model, with a 235 I6 and 3-speed overdrive. It's physically a large car, the same size as Chevy's Bel Air and Impalas, but weighs in at only about 3400lbs since it's a no-frills, radio-delete kinda car. Chevy's 235 is arguably a better-designed engine than Ford's 200, and with overdrive is able to push the extra 800lbs along at 30mpg as well.

The only problem with carb'd cars is that a lot of the little hidden tricks like DFCO and neutral at stoplights don't work on them. Other than that, they're capable of fine mileage, but automatics hold them way back, much more so than modern auto'd cars.

1980 Buick Lesabre is 3400 lbs too, not quite as no-frills, and has a trunk big enough to park my VW in. Mine's got a 252 (4.1l) v6. I hope to eventually change it to fuel injection, but I think it's a bigger project than I originally anticipated. I originally thought I could throw a TBI, ECM, a few sensors, and maybe a fuel pump on it and it would work. I've come to realize that it seems I'll also need to change the gas tank and all the gas lines, and maybe some other stuff I've missed.

I've not really noticed a difference in RPM in Drive or neutral while at a stop light. I normally flux between 575 and 625 in both. In fact in neutral it takes longer to drop below the 600 line. Of course the car has always been an odd duck.

1989 Caddilac El

The engine has to do a little more work to push against the torque converter compared to if you're in netural. If you've got approximately the same RPM either way, then it's feeding a little more fuel in.

I've setup a fuel rate gauge (see the "realtime monitoring for pre-obd2 cars" thread), and the difference in my 2002 GMC is miniscule but definitely there.

On my Odyssey V6, it idles at about .05 gph in gear, and in neutral it flips back and forth between .04 and .05. The resolution is really rough with numbers that low, but at least it shows that neutral uses less fuel.

Noticed something today on Marvin, he has a 3 speed hydraulic torqueflite derived transaxle....

Below 2000 rpm, if I put it into neutral for a second or two, then put it back in drive it appears not to engage drive until I press the gas again... thus you can be "neutral coasting" while still having instant access to acceleration should you require it... it appears to stay out even when you brake to a stop, and only engage when you touch the gas again. It does seem however to go back into drive fully when over 2000 rpm, guess that's because the tranny can still push the engine. Seems to need a certain amount of push from either side to engage, and lacking that stays out.

However, I think I remember one time a while back, I shifted into N, then went back to D and coasted down to a stop without brake use... and it sat there 5-10 seconds and then engaged drive slowly and began to crawl again. I didn't make any connections then about it staying in N though.

P&G (using N but not EOC) definitely works in an automatic. Proof is in the latest gaslog entry for my truck. I haven't gotten this kind of mileage in years, since the truck was brand new and I was driving 100% highway with the cruise control at 65. 18.31mpg!!!

I've been pulsing at 2000 to 2500 rpm, using as much throttle as I can while staying in third or fourth gear. It may not be as good as if it was manual, but it's sure better than nothing.

I've noticed on my '05 Passat that if I use the cruise control going over hills that it holds a higher gear longer than if I try to drive it myself. I even tried putting it in tip-tronic mode to hold top gear but the computer makes it down shift. I have been having lots of fun with coasting in N on the downhills. It does not seem to be making a big difference in my FE though.:(


jcp123- A newer tranny with OD and lockup would probably give your Mustang great highway mileage.


Phil

Vag-Com may be able to adjust your transmission behavior. Check on vwvortex.com or a Passat forum.

I have a 99 passat. The triptronic holds 5th down to 30 mph, and I've had great success with pulse and coast in N Increased mpg from 20 to 26 mpg in city driving.

phlp100,

You might try gradual acceleration downhill and then coast in N going uphill. You just need to accelerate enough to get about 5 or so over the speed limit and then coast to about 10 under the speed limit if you can.

I have tried this with great success. It takes some experience to fine tune the driving style and when to accelerate and coast but is well worth it. If you had a ScanGuage, you would probably learn on this faster than I have (haven't been willing to shell out the money for a SGII yet).

You can look at my Gaslog chart and see the gradual improvements over the past few months with neutral coasting up hill. I am now seeing about 39 mpg when I started with only 32.

Good luck!

Scott, I'm curious why you chose pulsing downhill and gliding uphill. Is it because you can get a more useful pulse without causing a downshift?

In my truck I've been pulsing uphill and gliding downhill, just like I do in my manual transmission car. The theory is that the engine produces power more fuel-efficiently at higher loads, and that the wider throttle opening reduces pumping losses too. (Additionally, your speed is more steady, which helps with the difficulties of P&G.) However, with an automatic it's tough to achieve those advantages because it will downshift. My strategy has been working for me, but maybe I'll try yours too, to see if it works even better.

I actually picked this tip up from PaleMelanesian and an article that he had forwarded to me.

I am not as technically adept as you on the shifting details of my auto trans (I am just a marketing guy) but I think the basic concept is to accelerate downhill and use the advantage of gravity to help multiply my speed acceleration while using as little gas as possible to reach speed. Then I coast uphill in neutral with my engine idling at 700 - 800 RPM. The more I can avoid using the gas uphill, the better off my FE.

Now, I can't always coast all the way uphill in Neutral so I sometimes have to shift into drive and maintain my slowest speed through the rest of the slope (usually around 55 mph or so on the highway).

I am sure there is a lot more science behind this technique that I am not totally aware of. I will let PaleMelanesian weigh in on more details on this technique if he chooses too. All I can tell you is that I saw an immediate 2 mpg increase in my fuel efficiency when I shifted from coasting in Neutral downhill to this technique. I can't guarantee that it works equally well for all vehicles but it sure works for my 2000 Civic Coupe.