spork

I'm only getting 15mpg city, is this normal? j/k.

I figured I'd consolidate some tips on improving gas mileage in this thread. I know people are sick of talking and hearing about gas mileage, but I figured this might be ok since it's more like driving tips.

So, I was getting ~16mpg mixed driving. Now I'm getting close to 18 mpg mixed driving (17.5-18.25). At least this is what I got on my last 3 or so tanks. This is what I do now:

1) I don't let the engine warm up. I wait for the engine to "settle" then leave. "Settle" means I'm around 1.25-1.5K rpm. (Advice from the manual)

2) When the engine is cold, I shift around 2.5-3K rpm. (Supposedly the engine uses double the gas when its cold? I think I heard that somewhere)

3) When coasting I leave the car in gear until I'm close to stopping, then I put it into neutral. (Supposedly the engine uses NO gas when coasting in gear I think. At least I read that somewhere here I think.)

4) When the engine is warm, I shift around 3.75Krpm, but I'll push it when I feel like it. I usually bring it up in the higher revs (7K+) at least once whenever I drive. (The second fuel injector starts working at 3.75K). Also if you're on a freeway try to keep it under 74mph (under 3.75K rpm).

5) I get into 6th gear the second I hit ~45mph and don't need to accelerate very much more. So if I'm in a 50mph street and there's cars in front of me, when I hit around 45mph, I'll change to 6th. But if I'm getting on the freeway, I'll shift however I want to shift, I just make sure I'm in 6th as soon as I'm done doing the bulk of my acceleration. I'm guessing this is probably the biggest reason for my mpg improvement.

<new recently added ones on edit>
6) Avoid idling. Idling = using gas, yes it is relatively minor but you're using gas and going no where.

7) Avoid shutting off and turning on the engine multiple times in a short span. This also means avoid many short trips. If you're making a lot of short trips and the engine doesn't get a chance to warm up, your mileage is probably going to suck.
</new recently added ones on edit>

Previously I was doing just doing tip #1 and shifting around 3.75K rpm all the time. I put the car in neutral a lot too when I coasted. Keep in mind that I also got better at driving manual but I did get a marked improvement (almost 2mpg!) since changing my driving habits a bit.

I also use Shell 91 octane. I tried 87 once and I thought I was getting better mileage for the first half tank, but then it wound up being the same as I get with 91 by the end. Oh and for other stats; I have a Grand Touring, 6 speed manual with about 7000 miles on it.

Anyone else have any other tips?

Fanman

Have you gotten the latest "N" flash. People who have gotten it have said the fuel mileage is a bit better.

Glyphon

1) i don't even wait that long usually. i'll just crank it, put my seatbelt on and i'm off. i think the rpms are still around 2.25k when i start out. and for those that wait for the car to warm up before driving, easy driving is the quickest (safe) way to bring the engine to temperature, and it doesn't kill your fuel economy.

2) i never take the engine above 3k before its up to temperature. it does run rich right after cranking, but i don't know about double the fuel, but then again i haven't gone out and measured it either.

3) yup, when coasting the car is in DFCO (deceleration fuel cut off), and uses no fuel...the momentum of the drivetrain keeps the engine spinning. if you are in neutral the only way to keep the engine spinning is if fuel is being injected.

4) i typically shift between 3k and 3.5k rpm in normal traffic driving. but when having fun, i'll take it all the way up to redline. and its the 2nd intake ports that open at 3.75, not injectors. only one set of those per rotor, iirc.

5) unless i'm going up a hill (which there are lots of around here), then i'll usually go into 6th somewhere in the 40-45mph range.

about the only thing that i do that you didn't mention that i do is keep it at 73mph or under while on the highway to keep the secondary intake ports from opening. and i've averaged 18.351mpg over ~2000 miles and 2 months.

fredw1

I think all the tips are good ones. I may get 18 mpg when I follow them, or 16-17 when I drive to have fun. The 1-2 mpg I lose by having fun increases my fillup cost by $1.00-$2.00. I fill up about once a week, so the total extra is $100 a year. If I wanted to save $100 a year, I wouldn't have bought the 8 to begin with.

Life is too short. I won't let obtaining maximium mpg dictate my driving style, but I will keep the tips in the back of mind.

Glyphon

oh, believe me, i have fun in my car; i typically hit at least 8k once a day, and have stepped the backend out more than a few times. but when you are sitting in traffic, there's no need to run out each gear. so by maximazing fuel economy in traffic, i have more fuel to play with when the opportunity presents itself.

MassiveAttack

No, there's an injector intake runner. 2 per rotor for the low power, and 3 per rotor for the high power.

I used to follow all these driving when I first got my car. I was getting 18-19mpg. I'm down to about 17 right now, but I've been being more agressive recently. Guess sometimes that mood hits...

--Massive

JeRKy 8 Owner

Here we go again with the flash bullshit. Anytime I ever upgraded to another flash on my last RX-8, my mileage just kept getting worse. If it ain't broke don't fix it.

Glyphon

could have sworn i read someplace that there was only 1 injector per rotor that supplied all 3 intake ports. guess i was wrong.

Haze

Spork, I think that you have just described the way that the 8 is supposed to be driven and what you are saying reflects closely what the manual says to do. Good for you and good post. I also think that it would be difficult to overestimate the amount of fuel that the 8 uses when it is running on choke during the warm up period. The less time that it spends idleing during this period the better, and that means starting and driving right away, conservatively as you describe, until warm. This also reiterates what Mazda has been saying all along. The only other thing that I might suggest is that if the car is driven hard or in city traffic a lot, to check the spark plugs earlier that Mazda suggests. I gapped mine in at 27,000 miles to the close end of the gap range (they were actually beyond the range at that point in their lives) and the power in my car and fuel mileage both increased. Enjoy those 8s. - H

charleybull33

I've a wide open 20 mile commute in the AM and a clogged 20 in the PM. 10 plus tanks of gas and 2700 miles driven. Lot's of trips to 9k, lots of spirited driving, reluctant to place in 6th. Best mileage on a tank 23, worst 19. I shift when I want, not per the book and have fun with it where I can - on-ramps, off ramps. I had prepared myself for poorer mileage but so far so GOOD.

Labop

I do everything you do except #3 and I'm still getting about 15 MPG. I tried tip #3 recently (three tanks worth) and I'm using MORE fuel than coasting with the clutch in.

Bimmerman

try adding intake/exhuast, should help if you leave you lead shoes as home

khtm

I thought the engine doesn't spin when you're in neutral. Aren't the RPMs at 0???

spork

That sucks. Well, all I know is after I added the coasting in gear and the get into 6th ASAP, I got about 1.5-2 mpg more than I usually did. I tried it for a few tanks and I don't get under 17mpg now (17.5-18.25) mixed (about 30-40% freeway) where as before I got around 16 (16-16.5 mpg).

The way I figure it is if you don't get at least 19mpg going 80%+ freeway (non stop and go) then your car is defective. Even when I was getting ~15 mpg mixed I jumped to just over 19 mpg when I did a roadtrip to San Diego which meant I did something like 70% freeway. There's not much you can do that's wasteful when doing a lot of freeway driving unless you're constantly gunning it to pass people, in traffic, or not in 6th gear.

I still have yet to break the 20mpg barrier though.

No, the RPMS on my car are around 750-900 rpm when I'm in neutral and the car is warm.

I try to do this but I just can't most of the time. I'm usually going high 70's on the freeeways unless there's traffic.

Michael

I got 12.25 mpg on my last tank of gas. I'm not a lead foot either. I didn't autocross on this tank. I'm doing all of the things in post #1. All city driving though. Virtually 0 highway.

FoxTypeR

Are you still up in Dallas, or is that tank from in Houston? I get around 15-16 here. I usually avoid the highways as most of my driving would be on 635 going the wrong way each way. If you're idling a lot with the A/C on, your mileage will suffer quite a bit just from that.

khtm

I guess that makes sense....0 RPMs means the engine is dead/off :o I'm a dumbass.

Michael

Nope, this is Houston driving. Lots of sitting in traffic/idling. It was at the dealer with this tank of gas so they might have left it running in neutral or something for an extended period of time. I've already got more miles on this tank than the last tank, so I know that the mileage will improve, but it doesnt look to be a drastic change.

Last tank was 152 miles / 12.4 gallons, yielding 12.25

FoxTypeR

Depending on what it was at the dealer for, they may have idled it for an excessive amount of time. I know when my wife takes a long time to leave work, my mileage suffers as I wait for her after leaving my building.

spork

I added these:

6) Avoid idling. Idling = using gas, yes it is relatively minor but you're using gas and going no where.

7) Avoid shutting off and turning on the engine multiple times in a short span. This also means avoid many short trips. If you're making a lot of short trips and the engine doesn't get a chance to warm up, your mileage is probably going to suck.

and i changed #4 a bit to reference the fact that you should try to keep it under 74mph in 6th gear when on freeways.

for me, AC doesn't seem to affect me much, but then again I use it sparingly so that's probably why i don't notice any effect.

Glyphon

i think my a/c has been off once in the past month and a half. i'd say it isn't really affecting my mileage much, but i don't have much no-a/c driving to compare it too (had the car for slightly less than 2 months).

ZoomZoomH

iTrader: (1)

short trips and frequent shutdown/startup is a MAJOR fuel efficiency killer in a rotary. Quite a bit of fuel gets dumped into the housings during startup.

RX-GR8

Stop trolling and change your screen name. You were already asked once.

Str8cold

I am averaging around 19.8 MPG, and as far as the STi comment above if I wanted to buy an over priced civic look alike with a craptastic looking exterior and the super basic interior I would of picked one of those up. Considering that people's reaction to the RX8 is one of pure envy, just curious what it must be like when people look at your Sti and wonder why someone would drive something that looked like a freakin turd on wheels.

Michael

I just filled her up, went from 12.25 to 13.8. I'll be driving to Matagorda Bay and back in the next few days so hopefully I can see what 6th gear will yield.