Yea 280 all city. My GF drives the 8 daily an her round trip with work is about 6 miles or less a day. I drove it around town a few times, but never saw any highway on that tank and the light JUST came on at 280 miles before filling it back up..

My GF also barely sees RPM higher than 5k from what I can tell though - I keep telling her to push the car more. Thats why I drive the hell out of it when I get a chance - keeps the carbon off :)

I'm still seeing about 230-250 miles per tank premixing vs 200-220 not premixing. I will probley never see 280 or better because frankly I drive the hell out of the car. I'm opposite your girl, mine probley never sees below 5k rpm other than taking off in first.

Update... I still have over 1/4 tank left... I'll be filling it up this week (Tuesday). But so far, Looks like Premix is in fact increasing MPG. Normally, I see less than 100 at 1/2 tank mark and I now see over 100 at 1/2 tank mark. I'll post here when I fill up on tuesday.

Well I had to fill up again after a long road trip w/ me driving - went 240 miles of highway/city mix with ME driving and driving hard! The tank took 14g to fill it back up, so really - to get to empty we could have put at least another 25 miles on it, so saying 265 of me driving vs 280 w/ the GF driving.. .I'd say the premix helped.

This week will be a better test though - I'm shooting for 300 to the tank w/ the GF driving, lol.

OK.. I filled up my tank today and here is my result..

10.1 gallons
166 miles.

16.6ish miles per gallon!!!

So, I have to say, didn't do much difference. I put more two cycle and we'll see next time..

^HAHA! I know why you get shitty gas mileage Phil...it's cuz you have Lightning Yellow! :)

Any idea what your fuel filter looks like, tire wear/pressure? What would you call your driving style (average 3-5k rpm, average 5-7k rmp, or average redline). Do you end up in a lot of stop and go city traffic?

I don't drive slow.. but I'm usually around 3-5k RPM range on cruise. City vs HWY, I'm about 50/50.

I haven't checked my fuel filter.. Don't even know where it is:) I haven't searched it.

Tire pressure is about 30-32 range. And since TPS, I know if I go below 28.

Could it be that I need an ECU flash??

here is a link that shows the mazda service bulletins. There is a new flash that came out this month I think but I'm not sure if it addresses anything regarding milage, but I have not read through what all the flash is supposed to be addressing.

http://www.finishlineperformance.com....php?pageid=11

I'm assuming the Fuel filter is in the tank, I can't remember if there was a access hole in the trunk like the FD has when I had the carpet up doing the strut bar install, I assume there is though.

Other than that, you might want to check your air filter, map sensor, and o2 sensor. I would say if any of those are bad it would have an adverse affect on your mpg.

I also came across lots of information about the 2004 rx8's haveing worse mpg than the newer models. Something about when the cars hit the united states the emissons didn't pass so the fix was to bump up richness or something to that effect, however I would assume that flashes past that point over the years would have addressed this issue with the 04's.

It seems with the complicated air/fuel ratio system the rx8 uses, that if you are doing steady driving (long distance highway at constant speeds), the map sensor is able to get consistant readings that are not changing much therefore the fuel economy seems to be better on a long distance drive where as with mixed driving the consensus is that fuel economy is worse based on the fact that your not getting readings that are staying in one spot but rather jumping up and down so the car is constantly readjusting the mix which can lead to a lower mpg.

I would think something is definatly off in your car though Phil, if you have just recently noticed lower mpg than previously.

Well, you might as well give up on the fuel filter...it's a combo piece part of the fuel pump. If the filter is bad the whole assembly must be replaced...$297 if I remember from when I was quoted about 6 months ago. Besides anybody really looking for better MPG's in this car might as well trade it in and get a Civic. I normally average 11 mpg in town and anywhere from 18-27 on the highway depending on how spirited I drive. But it's a sports car, I really don't care about shelling out money on fuel. Phil, be happy you're getting the mileage you're getting...I've talked to others that are far worse even driving all highway.

Also, when traveling the highway try keep your rpm's below 3800, it helps greatly since the secondary injectors don't open up until then. I know that's right around 70mph, but it does conserve the fuel..

Thanks guys Great info!!

Here is a quick FYI... I drove my MB FD to Nashville on Wednesday.. On my way up there I stopped for gas 2twice. After about 86 mile run I was averaging about 80MPH and filled up 3.6 gallons of gas.

From there to next gas station, I was averaging about 90+ MPH (with occasional 120+MPH pulls) and 117 Miles I filled up 6.2Gallons!!

Bottom line, I'm getting better MPG on my FD than my 8 :)

It took me 2hours and45 mins to go from Downtown Bham to Downtown Nashville with 2 stops.. I thought i did pretty good.

Damn Phil...SLOW DOWN!!! No wonder your gas mileage sux! HAHA! Oh yeah, with the distance traveled at a normal speed in my 8 I could have driven there on less than 3/4 of a tank...and only taken me about 20 mins longer to get there...food for thought. :)

Now I'm not saying you didn't get good mileage because you did! Hell, on your 117 mile stint you averaged 18+ MPGs!!! Not bad.:icon_tup:

There is no such thing as "normal speed" in a modified FD. :lol:

Another Update!!

I just went to ATL and just filled up!

I got 180 miles and put in 8.05 gallons! Thats about 22.22 mpg.

The trick was I went under 3800 RPM and set the cruise at 73MPH (RPM 3600-3700).

Hey Phil, I think I said that already...oh wait I did! HAHA!