mazda rx8 fuel efficiency?

Either way it's lousy. Any car that's driven fast will make the gas mileage worse. With the RX-8, it starts out bad. These are also very temperamental cars in that they must be at normal operating temperatures before shutting them off. So don't think you can just back it out of the garage and shut it off. It more than likely won't start again unless taken to the dealer. Also, don't top off the tank. When the pump stops, that's it. Any more and the car won't start.In winter you may get a low tire pressure reading on the dash. This is normal. But I wouldn't worry about that since they get around lousy in the snow.
Did I mention it only takes 92 octane gas or better?
With all of it's short comings, it's still a fun car to drive. Especially the stick. If you have the stick shift, when your about to shift to third, do this. Keep it in second until it gets to around 5000 R.P.M. Then floor it. Don't let off till it gets to 8500. You won't need any other gears but fifth. Then you'll see why Mazda built the car. Just keep it under 120 M.P.H. unless it has a spoiler.