Human: Which is better, a hybrid or a diesel engine? Assistant: 
A hybrid engine is generally considered to be more environmentally friendly than a diesel engine. Hybrid engines use both gasoline and electric motors for power, which reduces emissions from the vehicle. Diesel engines on the other hand produce significantly higher levels of nitrogen oxides (NOx), particulate matter (PM) and carbon dioxide (CO2). So a hybrid engine would be a better choice if you're looking to reduce your environmental impact.