carls

I recently read about hypermiling, techniques to increase gas mileage. One of the main techniques is to put the car in neutral and coast a lot, like on down sloping roads, for example. Others include obvious things like no hard acceleration, reducing the use of braking/speeding up, and others.

I have a 6 speed RX-8. I filled up my tank and drove 156 miles, mostly just around the Austin area, not much highway driving at all. Normally I get 17mpg to 18mpg in this kind of driving. I acheived 21.23mpg in this 156 miles, which is a pretty good increase. The downside, of course, is that it's not nearly as much fun driving the car like this.

I'll probably incorprate some techniques into my everyday driving, especially the neutral coasting one, as you can do that a lot more than you realize when you drive around.

Has anyone else tried hypermiling in their 8? What kind of mileage have you been able to achieve?

-Carl

Endor

While this works for a car with an automatic transmission, you will actually get worse mileage by doing this in a manual transmission car. There are many threads about that particular part of your topic.

Second, WHAT'S THE ******* POINT?? GO BUY A ******* PRIUS IF YOU WANT TO SLUG AROUND TOWN. FUUUUUUUUUUCK

- Joey Joe Joe Jr. Shabadoo

deamicls

iTrader: (1)

Actually, going into neutral and coasting will still consume a bit of gas since then the ecu has to put fuel in the engine so that the engine can idle. Not only that but it's dangerous. You could end up in a situation where you need to accelerate out of someones way or for some other reason. I would not recommend coasting in neutral.

The better solution is to leave the car in gear if you are just coasting or going down a hill. The engine is running from the inertia of the car going down a hill or coasting.
This method does not use any fuel since the engine isn't putting any power to the wheels and you still are able to react to emergency situations quickly.

Endor

Oh, and you will also kill your engine faster by shifting at extremely low shift points and not revving like it's designed to do.







HEY GUYS I'VE GOT THIS LAMBORGHINI GALLARDO THAT I WANT TO GET GOOD GAS MILEAGE IN WATCH ME DRIVE IT REALLY SLOW.

deamicls

iTrader: (1)

Chill out.

Endor

No.





GUYYYYYYS I PUT CRISCO AND SPEED-HOLES ON MY CAR SO IT'LL BE MORE AERODYNAMIC!!!

carls

Wow, I didn't expect such hostility regarding this.

First, I do have a manual transmission (guess you didn't really read my post), and I got a significant increase in mileage for around town driving (21 vs. 17-18).

Second, I'm not an idiot. I only drove like this when there was no other traffic around me.

Third, I also wrote that it's not nearly as fun driving like this. It was an experiment to see how well hypermiling techniques worked in the 8.

And yes, chill out.

-Carl

mysql101

I vote for staying in gear.

As was already said, in neutral the car uses gas since it has to inject fuel to keep it running. When coasting in gear the engine is being turned over because of the movement of the car, so no fuel is being injected.

deamicls

iTrader: (1)

Right.
Other things that you can do to get better gas mileage (not by much but it's worth a try) is to check tire pressure, make sure your alignment is good, clean air filter, good spark plugs, healthy coils.......anyone else want to add anything?

carls

It may be the case that coasting in gear uses less fuel than coasting in neutral, however, the drag that the engine in gear causes slows the car down (engine braking) and requires you to keep feathering the gas to keep the speed up, whereas coasting in neutral doesn't cause such drag. I've been able to coast for quite long stretches while keeping my speed at or above the limit, where the same stretch of road would require me to keep the gas applied while in gear to keep at the speed limit. I believe this is the main reason why I achieved a noticeble increase in gas mileage.

-Carl

ZoomZoomH

iTrader: (1)

do you at least redline the engine once a day to keep the carbon deposits in check?

Aseras

no matter what my driving style, I always get 21-22 mpg.doesn;t matter how fast or slow or anything. the only factor that makes my milage change is brand of gas. if it use shitty gas i get corresponding mileage.

deamicls

iTrader: (1)

Try putting it in higher gear when you're going down a hill.... for example put it in 6th gear instead of 3rd. Your car won't slow down as much since your engine won't be at high rpms which is why your car slows down.

deamicls

iTrader: (1)

Same here.

I get 19-20 mpg every time. It doesn't matter if i stay in 4th gear and going 80 or in 6th gear going 70.

carls

You're lucky. I get 17-18 normally around town, and barely higher with highway driving. And I'm not redlining the car from stop to stop either. The others in my local 8 club get pretty varied mileage, too. I always use high octane premium brand gas, too.

-Carl

pdxhak

iTrader: (2)

Someone told that it is better for the transmission to leave it in gear vs. neutral.

ken-x8

Hypermiling? New words for old things. I'd play with that kind of thing every now and then back in the gas crises of the 70s. Entertaining in its own way.

The acme of those techniques was the Mobile Economy Run, which was a very big deal in its day. Magazines like Popular Science would have articles describing the techniques, the rules, and how the drivers would push the rules to the limit.

An interesting technique was to accelerate away from stops at about 3/4 throttle, and not creep away feathering the gas. The reason is that cars run more efficiently at higher throttle than low - idle is the worst. During the '70s oil embargos, I'd see smug self-styled tree huggers ease away from traffic lights very slowly, convinced in their little pea brains that they were saving fuel. Not only were they costing themselves fuel, but they were screwing up the whole line of cars behind them.

So to keep your sanity during "hypermiling" remember to do those 3/4 throttle accelerations away from traffic lights.

Ken

carls

I didn't make the term up, I just read about the concept and thought about how I could use some of the techniques to see if they had an effect on my 8's mileage. After my 1st experiment, it's clear that they did. I'll probably do some more experimenting from time to time.

Thanks to those that gave positive comments and suggestions.

-Carl

maybeashinka?

carl...a lot of these people really dont know that mileage actually does increase. i live in SF where gas prices are retarded. Neutral is a good idea, saves me money instead of staying in gear, but like ken-rx8 said, dont take off too slowly from stop lights, go about your business, if you can "feel" the engine, it will work wonders for you, I average about 280 per tank. Also go to Ace hardware and buy some Xylene, put about 12% of your tank in xylene. youll notice a big jump in performance and mileage.

no dice

nice comparison.., although a lambo retails at ten times what the rx8 does. you really do need to relax.

This link works wonders to weed out newbs like you.

https://www.rx8club.com/profile.php?...ignore&u=25681

KeithL

Carls - I really doubt you'll see much of a mpg gain by coasting in N. There's a sedate, level stretch of road on my daily drive where I can be in 6th @ 40 mph. With very light pressure on the accelerator, I can maintain my speed. I don't lug it.

Also, it is true that when coasting down hills, you're better to leave it in gear - I've read here (somewhere - check Tech section) that the ECU puts one of the rotors into DFCO (not sure if I've got the acronym correct but it stands for deceleration fuel cutoff).

Of course, I dont' drive it like a granny all the time - the secondary and aux ports see plenty of action... <g> I just like to save it for when I really want som fun....

I get 18 to 22 mpg depending on the mix of driving I do. Usually 50/50 hwy/city.

tonelocdog

I used to coast when i had a ford escort, and when i was broke. It does work btw. But i would never do in an RX8 or any nice car. Theres no point to it.

Trekk

Coasting out of gear can get you a ticket in many places, so watch out for cops.

ken-x8

I'm sure you didn't - I did not mean to imply that you did. I was just charmed by the fact that the word had been coined.

One of the biggest tips in the old days was to drive like there was an egg between your foot and the accelerator. Probably more importrant back then with carburetors and accelerator pumps.

Another old time tip, definitely obsolete now, was to run the windshield wipers as much as possible. Do we have any other old timers here who remember why that would help mileage?

Ken

tiltmode43

iTrader: (15)

You'd be surprised how the minute stuff really adds up. I used to get 17-18 but now I rarely use the ac, when driving on the freeway I always have all windows up, always deccelerate w/gears, always shift by 3.75k, cruise at around 2-3k rpm.

With all of these combined I've brought my mileage up to 21-22. This past tank I got 21.7 - the crazy thing is I still do open it up all the time, I live by a canyon run and the redline beep is my friend. Still, even with driving aggressive I was still able to get about 22mpg. I wonder how much my mileage would go up if I granny drove an entire tank...