<human>:  What are the differences between diesel and gasoline?
<bot>: The biggest difference between diesel and gasoline engines is their combustion process. Diesel engines use compression ignition, where fuel is sprayed into a hot compressed air charge, while gasoline engines use spark ignition combustion, where a spark plug is used to ignite a fuel-air mixture.2 Diesel engines are typically more efficient than gasoline engines, due to the higher compression ratio and the fact that diesel fuel contains more energy per gallon than that of gasoline.3 Diesel fuel has a higher cetane number than gasoline, meaning it ignites and burns more quickly.4 Diesel engines generally produce higher torque at lower speeds than gasoline engines.5 Diesel is more resistant to pre-ignition, which can cause damage to gasoline engines due to detonation.6 Diesel engines tend to be more expensive than gasoline engines and require more maintenance.