Here's why:
* Lower thermal efficiency: Rotary engines have a lower thermal efficiency compared to piston engines. This means they convert less of the fuel's energy into useful power, leading to higher fuel consumption.
* Higher friction: The rotating housing and internal components of a rotary engine experience higher friction than piston engines, requiring more fuel to overcome this resistance.
* More air leakage: The seals in a rotary engine are more prone to leakage than piston engines, leading to less efficient combustion and increased fuel consumption.
* Higher operating temperature: Rotary engines run at higher temperatures, which can lead to increased fuel consumption.
However, it's important to note that fuel consumption can vary significantly depending on factors like:
* Engine size and design: Smaller and more efficient rotary engines can achieve better fuel economy than larger and less optimized ones.
* Driving conditions: Aggressive driving and frequent acceleration can significantly increase fuel consumption in both rotary and piston engines.
* Maintenance and tuning: Proper maintenance and tuning can optimize fuel efficiency in any engine.
While rotary engines are known for their high power-to-weight ratio and smooth operation, their fuel economy is generally considered a disadvantage compared to conventional piston engines.
