Why green cars are more frugal
Why are hybrids more fuel-efficient?
Vancouver Sun
Engine size
A gasoline-hybrid vehicle usually has a smaller engine compared with a conventional car. Most cars have a relatively large engine so that they can handle any driving situation -- called peak power requirement. Most drivers use the peak power of their car less than one per cent of the time. A hybrid's engine is sized closer to the average power requirement than peak power.
Electric motor
The electric motor on most hybrids might only have modest horsepower. Their secret is their torque. The Toyota Prius produces 295 lb.-ft. of torque from 0 to 1,200 r.p.m, which is more than adequate to get the car going without the gasoline engine engaging. A hybrid's smaller gasoline engine is usually powerful enough for it to travel at steady highway speeds. But when it needs to go up a steep hill or start off, it usually needs help.
Energy recovery and charging
Braking is used just to slow down most cars. In a hybrid car, kinetic energy is reclaimed by regenerative braking. Instead of just using brakes, the electric motor assists and, in the process, charges the battery at the same time.
Lightweight materials
A lighter car just means that it requires less energy to move. Lightweight metals such as aluminum are used extensively to keep down weight. From the hood to the alloy wheels, most hybrid cars have less steel than their conventional counterparts. Because some models, like the Prius, use the generator to start the car, it dispenses with heavy components such as the starter.
Aerodynamics
Most hybrids use aerodynamic aids to reduce drag -- the friction of an object travelling through the air. Some cars have smooth bottoms, as well as computer-designed shapes and spoilers to cheat the wind.
Engine shut off
Most hybrids shut off automatically when coming to a stop. The hybrid's battery ensures that accessories continue to run even when the gas engine is switched off. Some can accelerate up to 42 km/h before switching on the gas engine. On others, the gas engine is started once the driver releases the brake pedal.
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