ill get like 45 for 1/4 a tanks what should i do about this?

i use 93
its got 17-18k miles
2004

Driving in lower reps and higher gears helps raise gas milage correct?

 

Take a look around, there are tons of threads about gas mileage in RX-8.

One thing to take note -- the gas gauge is notoriously non-linear. All else being equal I will get significantly more miles on the 2nd "quarter tank" thank the first, and even more on the third "quarter tank".

The first thing you need to do if you are concerned, is quantify exactly what mpg you are getting. Fill the tank until the pump shuts off -- do not squeeze additional gas. Set trip meter to zero. Drive until most of the tank is gone and refill - again let the pump auto-shut off and don't add additional. Divide miles by gallons. Do this over several tankfuls and keep note of traffic conditions (stop & go?, City?, Highway?). This will at least give you a somewhat accurate idea of what you're really getting. Things like "X miles per tank" or "X miles per 1/4 tank" are fairly inaccurate.

Then, smile if you're getting over 17 mpg. This is not an economy car

Speeds and gears don't seem to matter all that much to this car, in my experience, as long as you're moving steadily along. The big impactor is stop & go traffic. The rx-8 gulps fuel at idle and that will kill your mpg in heavy traffic.

 

You should delete your post and search " gas mileage "

 

umm will do but first let me ask nubo this question ait

are you saying it would be more efficient not to shift into neutral when i go down hills?

 

Yes, search for deceleration fuel cutoff.

 

^^??When did he say that? It doesn't really make enough of a difference to risk having your car out of gear when you might need it to be in gear. I get 20mpg on the highway. Around town it drops a lot. The good news is it doesn't really matter if you go 55 or 95. You'll still get the same gas mileage!

 

its a sports car, and a rotary, not a corolla.

 

I guess it depends how you drive, but in city i get around 17 mpg with moderate acceleration, and another time I drove about an hour at 95 mph on the freeway in the middle of the night and you can literally see the the gas gauge drop. I only got 180 miles on that tank, about 14 mpg. The engine felt smooth as silk the entire way though

 

Apparently using regular unleaded gets you slightly better milage. I use 87 octane and routinely get 20mpg on average in 40/60 city/hwy driving.

 

doesn't 87 completely f your car up?

 

People have different results with different octanes. The rotary is quirky. Try different levels/brands.

I love it though cuz I can drive her like a maniac or like a granny and still get around 220 miles out of a tank.

 

umm just wondering if i were to upgrade my exaust and intake what are the chances of that hurting my millage even more?

 

Only would because you are flooring it more to hear the more noise it makes. Other than that, no

 

There are a bunch of threads on octane if you search around you'll get some good information. Basically I use 89 and never have any adverse affects. If I'm going to do a drive with the car club I'll throw in 92 since I'll be pushing it harder but I've never really noticed any performance difference.

 

The only time I used 87 octane was during the "gas shortage" and 92 was not available. I kept track through 3 tanks and I got worse gas milage. Almost 2 mpg. My drivng at the time consisted on about an hour to work on mostly curvy back roads. (85+mph and a lot of down shifting to keep the revs up out of the corners.)

 

I was talking more about idling in traffic. But since you bring up coasting, reportedly, leaving it in gear can be more efficient for this car because it will completely cut the gas if you take your foot off the pedal and coast with the gear engaged. Probably doesn't make much of a difference to average mpg unless you live in the Rockies... I usually coast in neutral out of long habit. And if you search you will find some heated debates on that topic too. There is a sizeable contingent who believe it is a death-defying stunt.

 

thanks didn't know that umm 2 bad it slows down the car though

 

LOL what is up with that - I might have to suddenly accelerate and I wont be able to afford the 1.5 second time it takes to react & put it in gear? I've heard that before LOL

 

That sounds like the daily commute of my dreams!!

 

Here is my top 10 list for bad gas mileage:

1. Verify your calculation point. Are you running the RX-8 all the way dry or are you re-fueling when the yellow light comes on??? If you are waiting until the light comes on, than you may still have 1 gallon to 2 gallons of fuel left (so you may have used 13 or 14 gallons as oppose to 15 gallons). Don’t make the mistake of calculating that you have run the tank dry from that point when you do the math.

2. Check your oil? Changed your oil filter? Are you in a hot climate? Think about getting the fan mod? How many oil coolers do you have?

If you are in a hot climate, there appears to be issues with temperature. A 2nd oil cooler (if you have one of the ones that don’t have it), fan mod (search for Looking for a cooler running RX-8? Or go to http://www.mazsport.net).

3. What is the octane level of the gas you are buying? Who are you getting your gas from?

The RX-8 likes 91 Octane or better gas. If you put in lower octane than you are supposed to than that may be the reason why you are getting lower than expected gas mileage. If you insist on using low octane gas to save money, than consider at least adding an octane booster. I’ve used octane boosters with Xylene, with great success. Xylene also burns well, without leaving a lot of deposits, like other octane boosters.

Note/Edit- There seems to be some debate about which is the better octane level. It seems higher Octane is better for performance, but maybe not for gas mileage. Lower Octane, but high enough not cause knocking, may be better for gas mileage. I think the best bet is to stick with Mazda's Octane rating when in doubt, but experimenting with different gasoline from different vendors and with different Octane ratings may help or show something.

I’m getting better gas mileage when I fill up at certain gas stations. I’m not clearly understanding this myself, but it appears the additive package from different gasoline companies are… different. Thus the RX-8 performs better with gas from certain gas companies. I think you need to test this on your own, as oppose to me telling you who to go to and this may vary from state to state or from country to country.

Also, people that have tuned their car with Int-X or Emanage or had their ECU flashed by a Pro-Tuner might have a different optimum octane rating than people with just a standard Mazda ECU flash.

4. You need to rev your RX-8 to at least 6K every day/every other day (higher for the M/T). Have you been doing this?

Some people are babying their RX-8 way too much. This can be hurting your engine, as oppose to helping it.

Very related, you may want to try a Fuel System Cleaner (Gumout, Slick 50, Redline, etc...) to remove carbon build up, gum, crap, etc... This would be helpful to people that have been babying their RX-8 and have not been reving it past 6k every other day.

5. Check your MAF ( Mass Air Flow) sensor/meter. Have it clean or replaced (if need be by dealer).

6. Check your Catalytic Converter. It appears that its possible for them to become clogged or damaged in various cases without the a CEL light going off. This can be the cause of an RX-8 eating too much gas or not accelarating "properly", so should be checked by an Mazda dealer.

7. Check your PCM (Powertrain Control Module) / ECU (Engine Control Unit) . It may need to be re-programmed/flashed. It may be injecting too much fuel when your engine is started an causing carbon build up and other issues. It appears that various RX-8 have problems with their ECU / PCM.

Note- results of having the ECU / PCM flashed appears to vary.

8. Check Air Filter or consider buying Cold Air Intake. May improve gas mileage.

9. Check O2 sensor. A defective one can cause overly rich mixture.

10. Another factor worth mentioning is customer expectations.

Don't expect your sports car to get fuel economy like an econo box. Gas mileage of most sports cars sucks. 17 to 24 MPG, or somewhere close (including 15 to 16 MPG every once in a while), would be normal to not unusual.

 

i get about 19 +/-1 around town, and about 23 +/-1, on the highway. car is 100% stock oem, 26k now, its had all the recalls/updates.

only thing i really do is make sure if i'm cruising the rpms stay under 3750, apparently the other 4 injectors turn on, and it goes rich at that point.

car does see red line and 100+mph at least once or twice a day/trip, too hard not too

 

1 . funny fact to that number 1 above .. my calculation point got me stuck 400yrds from a gas station .. that cycle's $ per mile increased by the cost of that little gas can

 

another tip, look as far ahead of you as you can. this will automatically have you driving smoother, and the slower your foot moves on the gas pedal the better the mpg.

made a trip this weekend, 280miles, and the light just turned on

 

At 50 mph you can cover a long distance in 1.5 seconds.

 

With the gas prices going up, I now fill up with 87 octane to save some money. There is no knocking and it seems like I get better fuel economy. This also differs with different gas, such as Exxon or Raceway...Raceway having better mpg IMO.

I was wondering if using 87 octane continuously damages the engine? What about fuel additives?