LawFitz

Very strange.

I just can't figure it out, but man this would be the perfect car for me if I could get the MPG they claim!

(By "they" I mean the others on this site not the EPA!)

MI_FamilyMan

Not to harp on a simple detail, but I would ask your dealer for proof that they did the N-flash. They should at minimum be able to produce some kind of printout/documentation detailing what was done and when.

And for the record, I've never done better than 18.x mpg on my 8. Although I've never gone on a long trip to get a 100% highway tank. I am assuming/hoping that I would break 20 mpg in that instance.

StewC625

The speed you drive on the highway makes a gigantic difference. I can make it swing 4 mpg on a highway cruise if I go from 85 mph to 70 mph at cruise.

That said, I'd much rather drive 85.

But, I did a 200 mile highway experimental look=p awhile back (last fall after my car had 3000 miles on it). For the first 100 miles I drove aggressively, cruised at 85 mph and basically lived la-vida-loca. Then stopped and filled it. Took 5.1 gallons. About 18 mpg,

Then, my next 100 miles, I set the cruise at 70 mph, did gentle accel away from stops and was a good citizen. Bang zoom, 22 mpg.

Draw your own conclusions.

MI_FamilyMan

I was afraid you were going to say that. Around here 80 is pretty much the norm on the highway, and on long trips, I definitely feel comfortable at that speed. I find the 8 to be a very comfortable highway cruiser and anything slower than that feels like you are going slow. I apologize to all those who wish to flame me for exceeding posted speed limits (it's 70 most spots here).

It doesn't surprise me that you see that kind of drop in mileage at those speeds, because by then you are over 4,000 rpm in 6th gear.

spork

Yeah, the thing is most people who complain about the complainers get decent mileage themselves and think it's user error.

I mean just look at some of the posts here
"There is something wrong with you if you think driving above 6k rpms should warrant good gas mileage... I am quite sick of hearing this myself..." (I doubt ANYONE complaining about gas mileage is cruising at 6K rpm or even taking it that high. Nice assumption though.)

"I bet I'd get 17 out of just about anyone's car."

In my case it very well MIGHT be the driver since this is my first manual transmission car. If it IS driver error I'd love to know and know how to correct my driving. I'm not going to drive granny style all the time... like everyone else said it's important to have fun with the car. I'd just like to have the OPTION of hitting 18/24. But like other people in this thread I'm getting about 16mpg mixed driving (or like 15mpg mostly city) which leads me to believe that it's probably not driver error that's lowering the mileage so much.

I think the general consensus is to get the best mileage outta the 8...
1) Keep under 4K
2) cruise at 3.25-3.75K
3) don't idle a long time for warm up
4) don't push the car when the engine isn't warmed up
5) don't take many short trips

I'm pretty sure most people who don't get great mileage have tried this. With this I get about 15 mostly city, 16.5 mixed driving, 19 mostly freeway going over 80. I'm pretty sure if I did all freeway going over 80 though I'd get like 21. But yeah I fully understand why people are sick of hearing this since this topic has been done to death on this forum. But obviously new members who didn't get lucky (or don't drive right) are going to be shocked and looking for answers.

LiveBlues

For those that were claiming that the people getting higher mileage must be stretching the truth, here it my truth. I have absolutely no reason to lie.

I just filled my tank today. My typical driving is an 8 mile trip to work each way. On the way to work, I am pulling from a side road onto a 2 lane highway that is usually pretty busy. I red line it through two gears to get into traffic then settle into whatever speed the road allows, usually around 60-65 for a ways, then 45ish most of the rest. The ride home usually doesn't start in such an exhilirating fashion.

I put in 8.9 gallons and had 165 miles on the odometer. 165/8.9 = 18.53 mpg.

Yes, it will drop some with a little more spirited driving, but not much. On the highway I've gotten 22-24 mpg.

For those that can't post these number, I truely feel for you and think that there must be something wrong with your car. Good luck in getting Mazda to work out the problem.

ThatREGuy

Who cares!! the car is awesome, if you live in the part of CA you might spend thirty dollars every three days, like I do, but thats because the car only shifts at redline. It has bad habits. And I do a whole lot of driving. Both for school, work, and pleasure. (if there wasn't enough pleasure already from driving) Im not kidding either, ten dollars a day! I have a ridiculous amount of miles!

snap-on

Heres another variable...how fast you depress the throttle and the load on the car.

I've been logging some data and I can see the injector pulse width go to higher rates when I "blip" the pedal VS gradual increase. I had a customer in the shop today and they were taken back as the "IPW" went DOWN in the 2500-3500 (2.1ms) range Vs idle(3.1ms) and I could see it quadruple when I punched it quickly(8.43ms) I could actually hold the car @7500 and the IPW went to 5.43.

This is an ongoing project for me and I have several cars with datalogger info. I have contacted Hymee to see if there is a way for his product will monitor this pid so we can sort this whole thing out.

Updates to follow.

Cheers
Snap-on

LawFitz

Thx for the reasonable response LiveBlues. At least you and MI Family man are civil about the topic.

I've been driving manual trannies for over 10 years and I have been very easy on her thus far. Shifting early, gliding to stops, etc. Gradually increasing her workload as I've broken her in. She's at 1500 miles and avging just shy of 15 MPG in 70% city driving.

I guess I'm trying to figure out with all of this if there's something wrong with my sweet new ride. I was hoping to keep her for a long time, but now I'm not so sure if she's gonna be doing 13-14 MPG or less when I start driving her hard. I luv her but it pains me to drive such a guzzling vehicle.

I had to pinch the budget to get into this ride and I was expecting closer to 20 MPG, so sorry for complaining too much. I just keep wishing that I could improve my sh*tty 15 MPG to closer to where you guys claim to be without sacrificing the driving experience too much.

I'll keep you posted as I add more miles to see if the numbers improve.

rx8cited

Another MPG factor I have not seen mentioned on this thread is tire pressure ..... stock summer tires get 32 PSI cold, snow tires get 36 PSI cold.

Don't rely on your TPMS to tell you when you need to check your air - its designed to warn you if the pressure is below 26 PSI or above 49 PSI. Check the tire pressure at least once a month with a quality air guage.

rx8cited

Yep you're right.

I should have said if my MPG goes up by 20%, then my old fuel budget is 20% higher than my new fuel budget.

For those of you getting **** poor mileage, if you have not already done so - consider trying 89 octane or even 87 octane. StewC625 and I use 87 octane.

andyp04rx8

I am on our 4th fill up. Odometer is just over 900 miles. The first two tanks
were a consistant 17 mpg using 93 oct. bp brand fuel. keeping the rpms at or below 4,000, city and highway,50/50. The 3rd fill up just averaged out to 19.5 mpg, same driving conditions but a different brand of 93 oct. I used mobile this time. odometer was 275 miles using 14 gallons. I am not worried or care about the mpg's and realize that these #'s will change once we start getting into the throttle a bit. This is with the latest flash.

Thanks
Andy P.

StewC625

That's the issue. Above 3750, it opens the secondary intake track and also changes the fuel mapping in the ECU for more throttle response.

Rotario

Filled it up on the way home last night. Took 14.4 gallons, and with 313 miles on the odometer, trhat works out to 21.7 MPG. I don't know if any of the following makes a difference, but I thought I'd include it anyway:

1) I use Shell V-Power 93 octane gas
2) Both the tranny and differential have had the stock oil replaced with Red Line synthetic oil
3) I changed the motor oil myself. Using Castrol 5W-20 dino oil
4) Car has 1950 miles on it total
5) For this tank and my (personal) test purposes, in addition to keeping the RPM's below 3750, I accelerated very gradually each and every time
6) I think the MPG that I got is absolutely best case, or said another way, I don't think I can get any better mileage, as I drove through this tank like a 99 year-old grandpa.

Best,
Bill

MTLbroker

Anyway you cut it, my fuel costs will always be lower than my bar tab.......
So I guess all's well.

StewC625

And that, ladies and germs, sums up the entire thread!

G8rboy

... and in addition to these variables, you've got crappy winterized gas in many of the northern states as well as year-round 10% ethanol gas. Too many factors outside of your control to consider in my opinion... the car was meant to have fun with, not worry about.

V_for_velocity

So this gas mileage thread to end all gas mileage threads ends up with dozens of posts of its own going in various directions. Pretty funny.

SilverStreak

rx8cited and G8rboy have good points. Tire pressure is often underlooked and most tires on the road are underinflated because most of us don't check often enough. In the Philly area the winter blends of gas required by EPA always seem to hit my mileage a bit (plus the extra idling/warmup times).

There does seem to be a wide range of mileage differences between our 8s. I tend to get 15-16 winter around town and 17-18 in summer. Best highway on a long trip was a little over 23 giving me an honest cruise range of 300 mi highway. My driving style is a mix of conservative around town and spirited on back roads/highway. The rotary engine seems to respond more like a motorcycle engine than other auto engines, the more you rev the more gas you use. I can range my motorcycle's mileage anywhere from 25 to 45 mpg just by how much I twist my wrist.

Nubo

I think we have conclusive evidence that there is no way to "Put An End To The Mileage Yap Yap"

SilverStreak

74 posts and counting. I agree Nubo. Bottom line enjoy the Zoom.

mjcampb

Has anyone ever suggested a separate section say:

RX8Club.com > General Topics > Mileage Issues

Oops, I can't believe I just added to another mileage thread, sorry.

agoodcave

Just for the record, I am getting EPA no.'s with 7500 miles on the clock.

MI_FamilyMan

Definitely keep us posted. I hope to hear about a success story. Maybe Snap-On might reveal some interesting things on the technical side.

MI_FamilyMan

Not bad, but not great... I'm sure Stew could do better... :p