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In defense of the 8's fuel economy

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Old 02-28-2008, 09:56 AM
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I've done this and Mazda keeps saying it is normal and I keep fighting them on it. I finally convinced them to do a fuel consumption analysis and they came back telling me that my car was getting 26MPG combined. After looking over their figures I identified their Mathematical errors and pointed them out, it was like talking to a wall. I am presently using a Scan gauge to try compile proof of a problem. So all I have seen from the RX-8 is terrible fuel mileage which Mazda says is completely normal. Last week I dropped below 11MPG for one tankful.

I placed a post once in the local members forum looking for a member willing to switch cars for a week so I could get another RX-8 mileage for comparison. Understandably I didn't get any takers. I also took it to two dealers. I'll bet you a G35 would be getting 11MPG.

Originally Posted by Roaddemon
The 07 g35 MT averaged 17.1 in consumer guide. See it's no better than the 8. Your one of few getting 13mpg avg with your 8. Get your car checked out. something wrong with it.

Last edited by Raptor75; 02-28-2008 at 10:00 AM.
Old 02-28-2008, 10:03 AM
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Originally Posted by Raptor75
I've done this and Mazda keeps saying it is normal and I keep fighting them on it. I finally convinced them to do a fuel consumption analysis and they came back telling me that my car was getting 26MPG combined. After looking over their figures I identified their Mathematical errors and pointed them out, it was like talking to a wall. I am presently using a Scan gauge to try compile proof of a problem. So all I have seen from the RX-8 is terrible fuel mileage which Mazda says is completely normal. Last week I dropped below 11MPG for one tankful.

I placed a post once in the local members forum looking for a member willing to switch cars for a week so I could get another RX-8 mileage for comparison. Understandably I didn't get any takers. I also took it to two dealers. I'll bet you a G35 would be getting 11MPG.
what was wrong with their math? I'm curious...did they add the city and hwy driving mpg numbers together?? 11city/15 hwy = 26mpg?!?
Old 02-28-2008, 10:10 AM
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Originally Posted by Raptor75
I've done this and Mazda keeps saying it is normal and I keep fighting them on it. I finally convinced them to do a fuel consumption analysis and they came back telling me that my car was getting 26MPG combined. After looking over their figures I identified their Mathematical errors and pointed them out, it was like talking to a wall. I am presently using a Scan gauge to try compile proof of a problem. So all I have seen from the RX-8 is terrible fuel mileage which Mazda says is completely normal. Last week I dropped below 11MPG for one tankful.

I placed a post once in the local members forum looking for a member willing to switch cars for a week so I could get another RX-8 mileage for comparison. Understandably I didn't get any takers. I also took it to two dealers. I'll bet you a G35 would be getting 11MPG.
I remember you posting that in the Chicago forum. Where do you live, or mostly drive? Another thing, some of us local members drove out to GingerMan for a track day last Spring. There were 4-5 RX-8s, and for the roundtrip we all averaged 22-23mpg.

I live in River North, but work outside of the city. Between that downtown/highway mix I've always been dead on at about 17-18mpg for the entire 63K. I use 87 octane, premix - though I've found no difference in mileage with or without premix, have changed my plugs about every 20K, mostly synthetic oil every 3-4K...just trying to give you a localized comparison. Both my RX-7 turbos had better gas mileage than what you're experiencing...
Old 02-28-2008, 10:57 AM
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Originally Posted by Rems31
what was wrong with their math? I'm curious...did they add the city and hwy driving mpg numbers together?? 11city/15 hwy = 26mpg?!?
If I remember correctly they were determining the amount of fuel used based on the % reading of fuel in the tank as reported by the computer start to finish. They were messing up the percentage addition and subtraction, I would have to pull the exact error from my records but it was pretty scary. The other less obvious problem I pointed out was that the fuel gauge is not that accurate, they denied it and said it was right on. I filled up the car after I left the dealer and found the readings they used were 1.2 gallons off. Went back and showed them it and they didn't seem to care, this was a shut case in their eyes. This was all the more frustrating because it took me so long to get them to do it then the screwed it up and didn't care. It was all a waste of time.
Old 02-28-2008, 03:28 PM
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There are some really interesting points on this forum and however irrelevant people find Raptor's comments, he's pretty much on the ball. Sure, love your car for all of it's uniqueness and positives. But these points are pretty spot on. With one exception, the torque (and I've raised this twice before). Torque in itself is meaningless unless you take into account the gearing. Mazda uses aggressive gearing which effectuates tremendous torque. People should be more concerned with 'wheel torque' than outright torque. In that regard, the torque is a non-issue.
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Wow, this is like a lawyer defending a mass murder by saying that "ya he killed a few dozen people but he is really a great guy who is a great still live painter".

Folks look at the simple facts.

- The Rx-8 is a fun car to drive, no arguments.

- The engine is small and light which is a contributing factor to its fun.

- The rotary is at least 15% less efficient then a piston engine.

- The rotary has very poor torque.

- No other car manufacture uses a rotary because of it's limitations (Poor power out put per fuel consumed)

- The RX-8 gets worst MPG then sports cars much fast then it.

- The RX-8 gets worst MPG and is slower then any other sports cars in it's class.

So if you disagree with any of these facts I would love to see you logic. If you agree with these facts then you are in agreement that the car is a gas hog plain and simple.

Enjoy your car, it is a great car but don't try to build into something that it is not.

Fan-boys < Facts

Last edited by lucifuge; 02-28-2008 at 03:30 PM.
Old 02-28-2008, 05:08 PM
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At least let's at least let's clear up some of the math here for those that don't know.

The 13b produces 2 power strokes (1 rotor face from each) per 1 revolution of the output shaft. That's 0.6L volume of air per rotor face times 2 to give us the marketed "1.3L".

The power cycle is the same as a 4 stroke engine. Therefore when comparing to piston engines in terms of air consumed per 2 revolutions (which is how we all rate 4 strokes) the 1.3L is actually taking in 2.6L of air in 2 output revolutions.

Also remember that the rotors are really only 'orbiting' the shaft at 1/3rd the output shaft. 9000 output shaft rpms is 3000 complete rotor obits, if you will.

I came from an 2.2L S2000. Both cars have their pro's and cons. The RX-8 is a good enough car for me to make the switch from that platform w/o missing what I used to have. Granted the gas mileage hasn't been great lately, but it's only a few points down from anything out there that's ~2.6L with similar output levels.

And for those that want more power and willing to sacrifice a lil more, there's always the turbo answer. Then you got your power back and still retain everything else that was good about the RX-8.
Old 02-28-2008, 06:05 PM
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Originally Posted by motorups
I can understand if someone purchases an rx8 and later feels the pain of money leaving thier pocket each time they gas up is more then they want to bear. And it is not really a 'cost vs benefits' formula in many instances. Sure we can whip out the calcuator and say for the 'X' amount of $$$ one loses by trying in a rx8 on a ABC car it would then take that person 5 to 7 years to recoup the lost $$ in gas savings they will get. To many of them I would bet they just don't care about that fact. It is just the feeling that each week (more then once a week?) they have to whip out that credit card or cash and pay to fill up their ride. Many times we just don't do the math before hand or at the time we trade in the rx8. And again, some just want something that gets better mpg, end of story...doesn't matter if the cost is greater nor if they will recoup the cost/lost in gas savings. They just know each time they fill up two things may happen (#1 they hopefully will fill up less often, #2 they will spend less $$ each time (or at least each week). It can be a strong emotional feeling to pay $45 to feel up compared to ... plus having to do it less often.

So far as a usable back seat goes...yes, for my six year old niece it works fine and I love it for anything else I want to take with me but not toss in the truck. A whole lot more room then the mx5 for sure.

This thing about being one of the five best handling sports cars....
well I'm not that good a driver but I do find the rx8 fun. To me it is work to enjoy the power band on the rx8 since (imho) I need to start at 4k then hit 5k before a real sense of power is 'on tap'. Then again I have only a drop over 1,000 miles on my new 07 ride so others know more about that then me. Being that I own the automatic the car would loop along at 2k if I let it. At 3k I feel at least the rx8 is alive and breathing and 4k and 5k is ok but once I have to 'work it' to bring her up to 6k...well, it just feels more like work to me at that point. Again, I'm new at this still (other rotary was an old rx7 back 1980). If I recall yesterdays long ride home from my brothers in manual mode then having that power on tap at 5k was fun and more importantly useful.

Score Card (to me):
Looks - 9
Ease of access to its power band - 6
(if more power was on tap at 3k or 4k I would rate it an 8 excuse the pun)
Usefulness of back seat (for adults) - 7
MPG - 5
(only because you have to be up in the powerband to find power)
Feeling - priceless (and can only be figured by the owner of the rx8)

Don't think I would want it as my only ride due to the low mpg but as a sports car with a back seat and great looks...
I will live with it, hopefully for many years to come provided they don't come out with a newer rotary engine next year (hell I'm too broke to even dream that thought anyway....)
enjoy your rides
You did pick an automatic - having to rev an auto is not that interesting. You can't fault the car for that though.

Last edited by Mobile; 02-28-2008 at 06:07 PM.
Old 02-28-2008, 07:26 PM
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- The Rx-8 is a fun car to drive, no arguments.
Yes

- The engine is small and light which is a contributing factor to its fun.
Yes

- The rotary is at least 15% less efficient then a piston engine.
Depends on what area you're talking about

- The rotary has very poor torque.
Is a 1.3 monster, what do you expect ?

- No other car manufacture uses a rotary because of it's limitations (Poor power out put per fuel consumed)
Wrong, is because its a lot harder to make than it seems. Check history. Now its too late for anybody to jump on.

- The RX-8 gets worst MPG then sports cars much fast then it.
Depends on which track you're talking about. and who is driving it.

- The RX-8 gets worst MPG and is slower then any other sports cars in it's class.
the question should be how *fast* do you want ? Drive a 350z like you drive in your 8 u will get the same if not worst MPG.

So if you disagree with any of these facts I would love to see you logic. If you agree with these facts then you are in agreement that the car is a gas hog plain and simple.

Enjoy your car, it is a great car but don't try to build into something that it is not.

Fan-boys < Facts
What about the fact that i can seat 4 ? S2000 anyone? Forget about 350z, thats the only 2 cars I can think of thats in our *class*

Have you mention that our 8 is the cheapest of all 3 ? Not couple hundred Im talking about as much as couple thousand dollar differents. I can get a brand new 8 for 24K (base model), whats the lowest you can get outa a 350z/S2000 ?

Its gas hog because people spend too much time on the pedal cuz its too much fun

Z34 will get even worst mpg. but for more power meh, why not ?

Last edited by nycgps; 02-28-2008 at 07:31 PM.
Old 02-28-2008, 08:02 PM
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Originally Posted by nycgps

the question should be how *fast* do you want ? Drive a 350z like you drive in your 8 u will get the same if not worst MPG.

.........Its gas hog because people spend too much time on the pedal cuz its too much fun ?
The whole point is, unlike a 350Z, you can't drive it calmly and have reasonable MPG. It still chews through fuel. No one has an issue with MPG at the top end, you expect that. But its usage when you just want to get from A to B in no fuss chews fuel disproportionately higher than most other sports cars in its class.
Old 02-28-2008, 08:08 PM
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I usually get exactly 17 mpg, but I filled up today and to my surprise I got 18.5 mpg! Who said this car gets bad gas mileage??

That is with mixed highway/city and taking it easy (shifting at 4,000) for about 85% of the time.
Old 02-28-2008, 10:12 PM
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yea I get about the same. Has anyone tried any supplements or what not to improve gas mileage for everyday driving?
Old 02-28-2008, 10:54 PM
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Raptor, man, by far you got the worst fuel economy on here...11MPG???? You towing a freak'n house?

Anyways, its fuel economy is not worth defending, I do about the same as my friend in his '06 Mustang GT, that's a 300hp V8!

But it's not such a big deal either, my wife's small SUV ('06 Grand Vitara) is actually as bad if not worse, and my old 1.8T four was **** too (once I chipped it).
Old 02-29-2008, 12:40 AM
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When I used to commute long hwy distances to work I used to average 22-24 MPG easily. No problem there. Kept the rpms within the primary duty cycle for most of the driving.

Now that I drive only 4 miles to work, which is barely at full temp when I shut her down, I'm averaging 15 mpg. Add to that now that I stop by the gym after work (across the street) and do a cold shut down to further the dismissal MPG figure.

You can see it all depends on the driving type.

But even with the lower mpg figure, I still come out ahead because of the close proximity of the destinations I end up filling less often. This is truly the only way to win at this game.

Last edited by F22C1; 02-29-2008 at 12:42 AM.
Old 02-29-2008, 01:59 AM
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Originally Posted by Flashwing
Anything with hybrid technology isn't going to be built for speed. I agree that the 16x may very well see better emissions and fuel economy. Mazda knows that the current RENESIS design won't stand up to emissions standards if they continue to tighten.


In my opinion, thats money well spent.
I disagree , if they could find a way to make some lighter batteries, you could feasibly use the insane always there torque to get moving real quick to offset the low torque of the rotary

but I truely feel that the information on what kind of mpg was there from day one way back in 03'. People could have you know.. done research on their cars before they bought it..
Old 02-29-2008, 06:39 AM
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My rotors are like children, no matter what, I love them, good or bad. I drive my 8for work all day every day, I havent had my it for that long and did some MPG tests for the first few tanks, but now I know what I'm up against, I just drive it and have fun. If people are worried about fuel then you probably should think about another car, not very fun thinking about MPG every time your foot goes down on a high RPM car, like I said in the begining of this thread, I drive it for more than looks and handling, I drive it because it IS IT for me, only one I want. RAPTOR I know you've been given heaps for having an opinion, but why not try posting some things you love about the car, if you cant then maybe its not for you. A rotory is more than a drive, its a personality, if you get what I mean??
Old 02-29-2008, 11:46 AM
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Originally Posted by midlife crisis
We regularly make trips of 800 miles and I compared the extra cost of driving the 8 compared to our Forrester. My highest reasonable "premium" for taking the 8 was only $25 with $3 gas. We're taking the 8 as long as no blizzard is predicted!
gas in bay area california is right under $4 lol for 91 octane. so if i see $3 per gallon gas, i thank god.

Originally Posted by StealthTL
Any car that shoots three foot flames out of its dual exhausts is probably not tuned to squeeze out every single mile per gallon.......


S
we all like the car, and its not the fastest car in class and is not the best MPG, but is one of the best handling. all we want is just a little better mpg, and hope mazda will tune the engine better in the future.

Originally Posted by New Yorker
No, mpg is not what this thread is about; mpg threads have been done to death here.

What this thread is about is the fact that, contrary to what many believe, you DO get something in exchange for mediocre mileage: you're getting one of the best handling sports cars on the planet - a direct result of the Renesis' tiny size and placement in the car.

(I oughta know; it's my thread.)
we are getting one of the best handling car out there for its price, but its just not enough sometimes. the rx8 and the Z gets the same track time on the top gear track, and that shows under power with good handling CAN be good. is just that our mpg is just worst than anything out there in class.

Originally Posted by midlife crisis
Also, do you think I'd even consider driving 800 miles in two days in a 350 Z or S2000 with luggage and a grumpy wife? They are not nearly as comfortable.
the 350z is very comfortable, the suspension is softer than our cars, and PLENTY of leg rooms, and head rooms, so is a very good touring car. s2000 is not.
Old 02-29-2008, 11:50 AM
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Originally Posted by Gish
I usually get exactly 17 mpg, but I filled up today and to my surprise I got 18.5 mpg! Who said this car gets bad gas mileage??

That is with mixed highway/city and taking it easy (shifting at 4,000) for about 85% of the time.
everyone says we gets bad gas mileage. i think everyone think that way too, is just that some people dont really care about the gas mileage.

IMO rx8 is a great car, i bought this car for its handling. many of us here had faster cars before and even gets better mileage, but i just want a nice handling car. but speak of the truth, if mazda dont make the rx8 better mileage in the future, i will not buy the 8 again. handling can be beat by mod the car, but gas mileage cant. sti would be my next ride.
Old 03-02-2008, 10:24 PM
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Originally Posted by nycgps
Yes

- The rotary is at least 15% less efficient then a piston engine.

Depends on what area you're talking about
Thermal efficiency, how much of the gas is converted to power.

Originally Posted by nycgps
- The rotary has very poor torque.

Is a 1.3 monster, what do you expect ?
Lets assume you really don't understand what I'm talking about. For the amount of fuel consumed this thing is a field mouse not a monster. This is the only really measurement that matters.

Originally Posted by nycgps
- No other car manufacture uses a rotary because of it's limitations (Poor power out put per fuel consumed)

Wrong, is because its a lot harder to make than it seems. Check history. Now its too late for anybody to jump on.
You need a little dose of reality here, every major auto manufacturer had test rotaries running and one after the other dumped them because of the inferior thermal efficiency. The difficulty in manufacturing was not the reason, believe or not I thing other car manufactures could figure out how to make a production rotary if they thought it was advantageous

Originally Posted by nycgps
- The RX-8 gets worst MPG then sports cars much fast then it.

Depends on which track you're talking about. and who is driving it.
Lets simplify this, think 0-60.

Originally Posted by nycgps
- The RX-8 gets worst MPG and is slower then any other sports cars in it's class.

the question should be how *fast* do you want ? Drive a 350z like you drive in your 8 u will get the same if not worst MPG.
No it really shouldn't. Drive the 350Z like the RX-8 and you still get better mileage. This has been well documented in several trade magazines.

Originally Posted by nycgps

What about the fact that i can seat 4 ? S2000 anyone? Forget about 350z, thats the only 2 cars I can think of thats in our *class*

Have you mention that our 8 is the cheapest of all 3 ? Not couple hundred Im talking about as much as couple thousand dollar differents. I can get a brand new 8 for 24K (base model), whats the lowest you can get outa a 350z/S2000 ?

Its gas hog because people spend too much time on the pedal cuz its too much fun

Z34 will get even worst mpg. but for more power meh, why not ?
Dude your blowing in the wind here, I agree with all your points here, except that stupid comment about "Its gas hog because people spend too much time on the pedal cuz its too much fun" It's a gas hog because of physics, that is why it is poor. Also throwing unrelated points into an debate is usually a sure sign of desperation.

Here are the Consumer Report numbers, they rates all cars identically so lets take a quick look at average reported fuel mileage shall we.

RX-8 = 18mpg
350Z = 20mpg
G35 = 19mpg
S2000 = 25mpg
STI = 20mpg (Older model)
EVO = 20mpg(Older model)
M3 = 23mpg

By the way every car in this list will take the RX-8 in the quarter mile and all but the S2000 are much heavier by least 300lbs. Again I love the car but I hate fanboys trying to change reality.

Last edited by Raptor75; 03-03-2008 at 10:53 AM.
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