RX-8 Fuel Rant

[GR-8]

Ah but my rant was that point exactly..... IT's A SPORTS CAR..... Online articles and Reviews need to stop saying it's a 1.3L 4cyl that gets bad mileage..... It's a 1.3L Putting out great power and is faster than Most N/A V6 vehicles with more than similar gas mileage as those V6 vehicles.... Der. Who buys a sports car for gasmileage anywho? Unless its the Tesla?

[roninsoldier83]

Well... everyone knows the RX-8 has poor fuel economy, I guess there's no sense beating a dead horse?!?

Although, I don't think the RX-8 should be considered a 1.3L, and I'm not the only one who thinks that. It won International Engine of the Year in 2003, but take a look at how they classified it:
http://en.wikipedia.org/wiki/International_Engine_of_the_Year

^^^It was listed under the 2.5-3.0L category, as they determined it's displacement to be a 2.6L. This has more to due with the number of rotations of the eccentric shaft compared to the number of rotations made by the rotor itself. The eccentric shaft makes 3 revolutions for every 1 revolution of the rotor. So, technically, the eccentric shaft makes about 3 revolutions to complete one full 4-stroke cycle (intake, compression, power, exhaust), opposed to a piston motor which takes 2 complete rotations of the crank in order complete a full 4-stroke cycle. So, others would argue the rotary is 1.5 times the displacement of it's piston equivalent... in Japan, where motors are taxed based upon their displacement, it is taxed as just under a 2.0L (1962cc IIRC).

Either way though, even if it is in fact a 2.0L or a 2.6L, depending on which method you subscribe, in the fuel economy department, it's an inefficient motor. Here's a good comparison of a car that has similar fuel economy:

2009 Mazda RX-8:
"1.3L" Rotary (arguably a larger motor)
232bhp
159 ft-lbs of torque
3064 lbs curb weight
16/22mpg fuel economy

Here's a car with almost 200 more horsepower, over 260 more torque, over 150 lbs heavier (more weight to pull=more work for the engine), has a claimed displacement of over 4.7 times the claimed displacement of the Renesis, and still has similar gas mileage in the city (better on the freeway).

2009 Chevrolet Corvette Coupe:
6.2L V8
430bhp
426 ft-lbs of torque
3217 lbs curb weight
16/26mpg fuel economy


^^^That's a good comparison, both having the same front engine/RWD layout. Both being manual transmissions, with the same number of forward gears & fairly sleek (read: aerodynamic) profiles. The real advantage lies in the LS3's ability to make ridiculous amounts of torque at a low RPM, allowing for tall gearing, partially negating the effects of it's large displacement, as unlike the RX-8, it's motor is highly efficient at making torque (which creates/sustains momentum) at a low RPM. In contrast, the RX-8 has to use shorter gearing to maintain freeway speeds. Since both of them have similar fuel economy (in the city at least...), ask me which one I would rather have

In regards to the comment about the RX-8 getting similar gas mileage to the 350Z (direct competitor).... with a manual, it's rated at 18/25mpg, a bit better than the RX-8, and I might add, it also has IMO, a more usable torque curve. For reference, in my old '03 350Z, I used to average between 23-27mpg mixed driving, with an all time high of 32mpg on the freeway... much higher than most of the real life fuel economy of most RX-8 owners, and even if they had identical fuel economy, I would rather have the torque curve of the VQ35 over the Renesis. IMO, it's not the motor that makes the RX-8 (although many would disagree), it's the chassis. Just my $.02

[goldrocket]

More air available for mixture, means more fule to burn. So a little bit less mileage.

[Billman]

Not necessarily less mileage. More air/fuel could allow for better efficiency, and therefor better mileage. It's not likely, but it is possible... We'll just have to wait and see.