Juge

They are more efficent in the design, since the insides rotate, which can happen naturally with rotational inertia, so it's smooth. Rather than having pistons that move up and down, which is why normal engines vibrate so much. Man, I'd love to see a rotary engine and see how smooth it runs.

Anyway, you meant fuel efficency, and it's not fuel efficent because of the same reasons a 2-stroke engine is less efficent than a 4; there are more fires of the spark plugs per rotation of the shafts. It makes it more powerful, but less fuel efficent.

But, I thought that per spark plug fire rotary engines would be more efficient than piston engines. In other words, if you consume the same amount of gas for both types (or all 3 types) of engines, wouldn't the rotary be the most powerful? I know that there's less force required, since it doesn't have to top and accelerate the pistons, so it should leave more power to eventually reach the wheels.