1. Problems with emissions control. Rotary engines use direct oil injection and this means oil is constantly burning with the fuel.

2. Economies of scale. Due to the complex nature of rotary engines very difficult to repair in relation to piston engines and very few people are trained to maintain and build these engines

3. Fuel consumption. Rotary engines are notoriously expensive to run on fuel.

4. Lack of low down torque/driveability. Rotary engines makes a tremendous amount of power at high RPM but insignificant torque in the lower rev ranges.

5. Ignorance. If more people disregard all of the above and eventually get to drive a rotary powered for for a while, they'd be converted. Unfortunately almost all rotary owners are petrolheads and adrenalin junkies!

Straight/Inline engines, V type engines, Rotary engines and diesel engines

1992-1995 2.5L 4cyl

They are both internal combustion engines

jet engines, turbojet engines, turbo-prop engines, four-stroke piston driven engines... Can you be more specific?