KKMmaniac

I know this topic has been discussed in the past, but now that we have some hard numbers, (ok, so the official EPA figures still aren't out yet) mainly from Car and Driver, I want to hear how others feel about this topic.

I tend to forget where I heard what, but quotes similar to this one: "Also, it's more economical than the RX-7's 13B, getting up to 30 percent better fuel economy in certain driving situations." (Road & Track, April 2002) have been made in regards to the Renesis and RX-8. Well, the RX-7 (FD) 5-speed was EPA rated at 17 mpg city/25 mpg highway. Car and Driver, in their September 1993 test found the FD to average 14 mpg on a 1500 mile trip. In comparison, the RX-8 was EPA rated by C and D in this April's issue at 18/23, with 15 mpg being the average on a 500 mile trip. This doesn't look like a noticeable improvement to me.

I realize, if we're after performance, it is unlikely we are going to get economy-car gas mileage results. However, in the normal mid-rpm, ease down the throttle pedal, day-to-day commute, I was hoping the RX-8 would out-do my WRX in fuel mileage (20 or so mpg) by a tiny bit. I would also argue, the EPA numbers shouldn't be affected by the opening of the third port, as that occurs at a fairly high RPM range that probably wouldn't occur in regular (careful?) freeway driving.

Does anybody else think my gripe is at least somewhat legitimate?

Hercules

I dunno... I saw the same thing and was concerned, but a *lot* of that mileage has to do with HOW they were driving the car.

I think that they were running typical 'track days' almost every day on the RX-8 and for the most of us, that won't be the case. I believe the stated figures so far are something like 21/24 or something like that... which isn't great by any stretch but not terrible either.

Time will tell.. I don't know about mileage yet.

SA22C

Car and Driver typically flogs the hell out of their cars, so I wouldn't be too concerned about the reported mileage. IIRC, they got 12 mpg in the Mustang and 16mpg in the G35, so the RX-8 is right where it should be.

Skyline Maniac

So do you know about the 'fun to drive' factor, the 'sufficient torque' and 'backseat practicality' yet? or are those also 'time will tell' things?

rx8daniel

My opinion: time has already told me having had earlier NA RX-7s that fun to drive will be just fine, thanks. And back seat should be great, unless somehow I get the job of transporting members of a basketball team, a lot. Torque isn't even an issue - if I needed torque I'd get a turbodiesel truck. Agree Herc??

bdclary

Yep. I was expecting at least 20 mpg in the city and around 27-28 on the highway; I get 17/23mpg in my 86 GXL.

I'm not disappointed in the city mpg. I think if you drive for fuel economy (keeping the revs below 3500), then 20mpg shouldn't be out of reach.

However, the highway mpg bothers me simply because I think 6th is too short. Around 4,000 rpms for 80mph? 6th should've been a true overdrive. If I remember right from Buger's post, theoretical top speed comes in fifth gear, so 6th wouldn't even be used on the track.

Brian

yaksplat

Right now I have a '94 Integra gs-r and at 4000 in 5th I'm doing exactly 80. I love the gearing in my car

FritzMan

I mentioned it in the Canadian forum after detailed specs from Mazda were relased (http://www.rx8forum.com/showthread.p...5&pagenumber=2).

The RX-8 will do, in litres per 100km, 12.8/city and 9.2 highway. That results in approximately 18.5/25 US MPG (http://www.pege.org/fuel/convert.htm). Curious that the auto tranny does even better on the highway with 8.8l/100km.

m477

Is 18/23 the official EPA rating, or the C&D estimated rating? I'd be really surprised if the highway rating of the RX-8 ends up being worse than the FD, especially since there's the extra tall 6th gear...

MikeW

I don't know if any of the older wankel engines used exhaust gas recirculation, but with only side ports, there could be egr.

Hercules

As per the C&D article, I sure do.

Zio

If it gets worse gas mileage than my tribute, which I dont think it will, i'll laugh. My trib gets like 18 city 25 highway.

Quick_lude

4000rpm at 80mph in 6th gear, if this will be the case is not very tall imo.. My car is at about 4200rpm at 140km/hr.. I would have thought with 6 gears the 8 would have a taller 6th..

zoom44

irish car mag says it's just under 30mpg clicky-clicky

threeputtwash

Don't forget that the British (and I'm assuming Irish as well) have a different gallon than the ones here in the U.S.
1 British gallon = 1.201 US gallons
So the British (and Irish?) should have about a 20% better mpg rating...

chenpin

wow, i've never read that article.

Favorite quote: "Imagine the angst the RX-8 will cause. An absolute peach of a sports car and innovative to the nth degree."

zoom44

i thought that might be the casehere is where the rest of the article can be found:D

Donny Boy

I too was hoping to get at least 30 mpg on the highway ata steady 60 mph. This is not too much to ask for, especially after the revelation that the RX-8 gets up to 30% better fuel economy than the last RX-7 in certain driving situations.
What better condition than steady highway speed?

yaksplat

Exactly. At steady highway speed, all that the engine is doing is countering friction from the road and air. Hrm, why is it that I have an urge to draw a Free-Body Diagram?

I think I was brainwashed in engineering school

~Jim

rxeightr

For what it's worth, the MazdaUSA website now lists the EPA figures:

6 sp. manual -- 20.4 mpg City 30.2 mpg Highway

Auto -- 21.3 mpg City 31.6 mpg Highway

Certainly a lot better than what Car & Driver experienced. I'd guess if you have the capability to keep your foot off of the accelerator, you can get pretty decent gas mileage.

khoney

As if that'll ever happen... )

Telepopmusik

Looks like Mazda has left no stone unturned- great looks, great performance, and excellent fuel economy!

MikeW

That isn't exceptional fuel economy, it is okay. Honda Accord V6 automatic 21/30 on 87 aki fuel.
An you need 90 (R+M)/2 too for the renesis. I am still looking for 90 AKI mid-grade
http://www.rx8forum.com/showthread.php?s=&threadid=877

wakeech

considering the level of performance from the engine, its intended use, and the fuel consumption numbers of the ol' 13B, these numbers are incredible.... although yes, you can find many an engine which can sip the fuel more effectively, even in a bigger car. *shrug* who cares?? as long as it delivers where it has to (which it does in spades), s'all good.

Telepopmusik

Compared to its intended competition (350z, G35, IS300- etc), the RX-8 delivers excellent fuel economy.

Yes, I do know about the mileage of the Accord V6, because that's the other car I'm considering. But I have not heard one owner who has achieved close to 30 mpg on the highway, 24-25 is more realistic. These are two different types of engines, and the Accord's gearing is ultra-low (6200 rp/m redline and 5500 rp/m for the 4 cylinder), which is one of the reasons for the high fuel economy, and comparing the Renesis to the Honda J30 is sorta like comparing a F-16 to a 747.

The Renesis is the engine that will make even the most ardent Mazda and rotary naysayers (like even me a few months ago) stand up and gasp in awe. Low emissions, the best fuel economy in its class, and decent power without a turbo.

Anyone willing to bet me that the RX-8 automatic will be faster in the 0-60 and slalom than the Accord V6 Coupe automatic??? :D