Final answer:
Gasoline engines have higher fuel efficiency at lower speeds and typically produce lower carbon emissions, but have variable maintenance costs and less torque compared to diesel engines. Engine efficiency around 25 percent is constrained by the engine's thermal limits.
Step-by-step explanation:
When comparing gasoline engines to diesel engines, it is important to focus on the characteristics that define their performance and environmental impact. One advantage of gasoline engines is that they typically have a higher fuel efficiency at slower speeds, which is beneficial for everyday driving habits. It is also noted that gasoline engines may generally produce lower carbon emissions compared to diesel engines, contributing to less environmental impact per mile driven. However, depending on the specific design and use, maintenance costs for gasoline engines can be lower or higher compared to diesels. As for torque output, this is an area where diesel engines often excel, offering higher torque at lower engine speeds.
The overall efficiency of an engine is crucial in understanding its performance. Typically, a gasoline engine has an efficiency of around 25 percent, meaning that a quarter of the fuel energy is converted into mechanical work, while the rest is lost as heat. The efficiency is determined partly by how much heat an engine can withstand before overheating, and since automobile engines have a limit to how hot they can get, their efficiency is not 100 percent but capped by thermal limits.
Furthermore, cars have been increasingly designed to be more fuel efficient, getting more miles to the gallon due to advancements in technology.