werd

 

I highly recommend this thread

hac provides some good info on grades of gas and especially the additive packages that go into the various branded (i.e., "major" brand, and "non-major" brand) gasolines.

Sticking with Shell 93 -- for both the octane AND the additive package...

 

I have always used low octane in naturally aspirated rotaries and I always will. They love it. $3 more a tank may not sound like much more to some but when you drive 30K+ miles a year, that's alot more money. Add to that the ridiculous gas prices right now and it is just downright expensive. $3 more a tank for a slower burning fuel. No thanks. It would be cheaper to use low octane and throw in a dollar bottle of octane booster if I wanted that.

 

I disn't mean to try and sound harsh. But I went into buying my car knowing that it was going to get lower gass mileage than what was estimated on the EPA sheet. So I just suck it up I guess. I'm one of those 12 to 16 mpg guys and I just make due. The real beef that I have is, and it's the one that I should of made a point of is that you can find 10,000 topics on what is the best oil, ect. Everyone wants to put in the best oil, but for some reason when the owners manual says to use premium, people use standard. I just don't get it. That was my main point, all the other stuff was secondary. Like I said, pet peeve, and in no way meant to sound harsh.

 

Beachdog had a really great point. If I drive mine to work daily, 2.5 miles each way the milage sucks. If I drive the beater to work and play with the 8 on weekends the milage is much better even in city driving, no that doesnt mean 2.5 mile trips and letting her cool again. It's how you drive it. Oh and the manual calls for 91 octane. I always fill up at half tank, one at 89 one at 93. We don't have 91 around here, works out great.

 

I've experienced the same results. I usually ride an express bus (from my back door) to work, but if I need to drive to the metro stop to catch a commuter train (to get in to the office extra early when I'm on an early schedule -- like this week), it's only 2 miles away. Over time, that series of 2-mile trips fast-cycling from just warmed-up back to cold just chews gas. I'll get around 15-16 mpg. I can take it out on the open roads and really wind it out and I'll get 18 mpg. Long trips in cruising mode (usually 70-80 mph) yields around 23-24 mpg.

We've got some long road trips coming up this Summer, so I'm really curious to see how the mpg fares over extended periods of continuous cruising.

 

Well the big difference is oil = ~2-5 bucks per 3,000 miles.

Gas = ~600 extra bucks per 3,000 miles if you use the good stuff.

one's a *little* easier to swallow.

And yeah I noticed I can push the car harder and there's little difference in gas mileage. I really do think a lot of the mileage difference might be how many times you start your engine.

I usually get 16-16.5 mpg. Last tank I actually pushed it a few times for the heck of it and I actually came up with 16.7 mpg. Strange.

 

I drive my 8 for the fun of it. I don't work (currently) so I just polish and drive. I'm getting 16-19mpg screaming around or driving like grandma. I put whatever fits my fancy in it 91, 89, or 87. I top my tank off every day as the prices are going up each day. I try to rotate the octane so I'm probably keeping an 89 in it at all times. 16-19 isn't bad fuel consumption in my mind for a incredibly fun ride. My last car was an 01 Outback which got 20mpg and was fun but not 8 fun. B4 that was a 98 Dodge Ram with a 360, K&N, Flowmaster, and upgrade chip and that got 12mpg, again fun but not 8 fun. As long as my 8 stays together I'm very satisfied with the fuel consumption. My only concern is that the engine rasping is "rotory knock" which I've had since it was new no matter what octane I put in it, but quite honestly, I'm not that worried about it, it always goes zoom-zoom....

 

That really is weird. I think that's probably an anomaly! Cuz I know if I started my car in the driveway and left it on for hours ... I would be getting 0.1mpg (have to account for the trip from the gas station).

 

OK, I suck at math, but assuming a $0.20/gallon differential between 87 and 93 octane, you're looking at $600/3000 GALLONS. The only way you'd pay $600/3000 miles is if you were getting 1 MPG.

 

let me say this, myh other car is a honda civic hx. ~ 48-52 mpg highway for me, i have a 52 mile commute one way to work so it's a must except when i break out the rx8 for a feild trip. This car runs like crap on unbranded gas and any premium kills my mileage ( like 5-10 mpg off ), walmart/murphy gas sucks, hess sucks, chevron,mobil,shell ok. Stick citgo in there though and it's like 50 more hp and it run WAY better. I don't know why, it just does. I use that car as a barometer for fuel quality. Sometime when I'm traveling I'll get no name and it's a toss up and the car will run good or run like crap. there's a definite diffrence in gas quality.

 

I've seen a difference in quality between companies as well. My Honda generally runs fine on Exxon, Chevron, RaceTrac, but is absolutely terrible with Shell and a few others. That's pretty strange.

 

myfuncar answered your question on the sound--it's a clattering noise (it's probably called 'knocking' more for the action that actually occurs from the misfiring rather than the actual sound it makes). To me, it sounds like those manual toy machine guns that we all used to play with. Again, for me, it only happens at high rpms.

Also, the 'rough idle' isn't such that your car acts like it's a hoopty car with hydraulics straight out of a rap video. It just vibrates more noticeably than when I'm using 93. These are minor inconveniences at the time they happen, but, for me anyway, they are indication enough that I could be doing more long-term harm to the engine than is worth the few dollars I save at the pump.

 

Hmm, I might switch to Shell just to try. I use Mobil/Exxon now cause they are on every corner in MA. I usually get around 19.4 mpg with mostly highway.

 

Hi all, new member first post, my 05 has 1601 miles and the best I have gotten EVER is 17.35 the worst about 12 all on 93 octane ... am considering challenging their mileage estimates much like the previous horsepower fiasco this borders on fraud.

 

Welcome to the Club, zenlawyer

Before you go to Mazda NAO complaining about the mileage, consider that other factors come into play besides the mere numbers you are calculating. For instance, I believe someone here said a while back that Mazda had the DSC and TCS systems turned off when they produced their estimates. You might see if that makes a difference, at your own risk. I don't see as much of a difference personally when I do it now that my car has passed the break-in phase. Also, remember that doing the calculations based solely on miles driven and perceived fuel consumption between fill-ups is still far from accurate, which will partly explain why there are varied mpg estimates across the board (and which is why this discussion will keep popping up every other week ).

 

Huh? Wha?

For the "good stuff" to be $600 per 3000 miles it would have to cost $4/gallon more than the "not-so-good stuff".

Since in all actuality, the "good stuff" (Premium) is 15-20 cents (we'll say 20) more than than the other stuff, the difference is actually more like just $33 per 3000 miles.

Granted, as you said, it's more than the $5 per 3000 miles for the oil -- but a FAR cry from the $600 per 3000 miles that you claimed. Unless they're driving 3000 miles a week, most people would never notice the difference between paying for Regular and paying for Premium, since it works out to a whopping $10/month for the average driver.

 

Mazda does not make the estimates, the federal government does. Those are the results of federally mandated EPA testing, which Mazda has no say in.

It wouldn't matter if the EPA said that the RX-8 got 30mpg but Mazda knew that you and I would likely only get 15, that sticker is a result of federal testing and must have their results on it.

If you got a problem with the numbers, you're going to have to take it up with the EPA.

And for what it's worth, you shouldn't really be gauging your mileage until you break 10,000 miles or so. Every car I've owned has gained 2-5MPG on average in the tanks between 10,000 and 15,000 over the tanks between 5,000 and 10,000 -- and yes, I track my mileage religiously. And for no good reason either, as gas prices and mileage don't bother me in the slightest. I just do.

 

In some cases the manufacturers would love to be able to advertise more real-world MPG estimates, especially in the case of the Prius. Everyone knows with it that the EPA estimates are a lot higher than real people experience with it, and Toyota knows this, but they have asked to be able to advertise lower ratings so people won't feel so disappointed, and been told no.

 

I'm not talking about cost at all, this is just strickly from a quality point of view. But then we go back to my orginal post on going cheap on a car that wasn't meant to be. But I'm beating a dead horse. It might be different if I put 30k a year on my car but I'm lucky if I put 6k on it. So talk is cheap I guess and I understand everyone elses point of view.

 

There should not be much variation, but its interesting - seems like there is. Either that, or, equally likely, there are too many factors at work here for identical engines to produce the same gas mileage, oil consumption, etc., Factors like temperature, driver habits, lengths of trips, cool downs, and then throw in who's had which TSB's performed and who hasn't, and that could also account for the 13-19 MPG reported for city driving and other differences.

One thing we seem to all have the same experience on is the FUN!!!

 

I have noticed that when I drive ‘aggressively’ the 8 sucks up fuel like a pig rolling in chit. On the other hand when I drive like a dinosaur the 8 gets really good gas mileage, I’d guesstimate between 20-25 MPG. Oh and I only use 91, its not my daily driver.

Of course it's waaaaaay more fun driving like a bat out of hell. :D

 

Oh, great. Enter the ambulance chasers....

 

i think this all boils down to how you drive. If you never drive at WOT or in the high revs then 87 will probably work. im inclined to think that those who switch to 87 also dont drive the car to the limit

 

just topped my tank of with 93, got about another 25 miles , 13.7 gallons to 330 miles. 24 mpg. that's fantastic.. and that was with me doing a large amount of city driving. We'll see how it goes now.