This data suggest that merely installing an overdrive
    unit on an RX8 will improve the MPG to 35 on the highway.
    The RX8 engine is turning 3000 RPM at 80 MPH.
    A Corvette turns less than 2000 RPM at 80 MPH and gets 25 MPG.

    Both cars need less than 40 HP to go 80 MPH.

http://www.superchevy.com/technical/engines_drivetrain/transmission/0411sc_od_copy/ <http://www.superchevy.com/technical/engines_drivetrain/transmission/0411sc_od_copy/>


    "It's been 2 decades since Detroit began offering overdrive transmissions as original equipment in virtually all vehicles rolling off their assembly lines. And while the OEM's intent was to improve fuel economy <http://www.superchevy.com/technical/engines_drivetrain/transmission/0411sc_od_copy/# <http://www.superchevy.com/technical/engines_drivetrain/transmission/0411sc_od_copy/#>> and decrease engine wear, it wasn't long before enthusiasts realized the performance gains that were possible by adding another gear with a ratio of less than one-to-one. With overdrive in high gear hot rods could benefit by using a lower (higher numerically) rearend gear, which translated to greater acceleration without the inconvenience of higher rpm while cruising at highway speeds. This was akin to having your cake and eating it to, as high-output engines were allowed to run in their power range while blasting from stop light to stop light, only to be given a reprieve when it came time to hit the open road. "

    Paul Lamar



I would disagree with this assertion. We have a friend living in the apartment under our house, and he has an RX8. He claims an improvement of 2 or more MPG keeping the rpms in the 3500 to 4000 range instead of lugging it down in 6th gear. We live in the Florida Keys, with the speed limit 45 for 20 to 40 miles at a stretch. For a long time he was complaining about the mileage he gets around here. We talked about the airplane engine version, and how its "happy place" was around 6k. I suggested he get his rpms up a bit and see what happened. For a week he ran in 4th and 5th gear, and reported a gain from 14 to 16 mpg. While my diesel is quite happy running at 1600 rpm at 65 mph getting 24.8 mpg, I think the rotary needs a bit more speed to breathe better.

Highway speeds might change it a bit, the next time he goes to Miami maybe he can check it.

Kevin Alderman

My RX8 will happily run at 45 MPH in sixth gear at 2200 RPM.
It will pull away at zero MPH with out depressing the throttle pedal
in first gear from 650 RPM. It gets a steady 25 MPG at a cruise control setting
of 65 MPH.

I would have to ride with this fellow. Some people have a bad habit of pumping
the gas pedal to maintain a fixed speed.

It runs at stoichiometric 98% of the time.

You can calculate the fuel burn from this OBD II data on the RX8.
One pound of fuel per 14.7 pounds of air.

Paul Lamar