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Internal combustion engines are notoriously inefficient, running at less than 30 percent efficiency.

properly. Friction between the tires and road surface also slows the car down, and that reduces efficiency. If tires had less surface contact with the road, they would be more fuel-efficient, but not very safe. Tires must be designed to compromise between performance and stability for safety. Drag forces on the car also reduce efficiency. The necessity for braking alsomeans that energy is lost to slowing or stopping the car. Energy is also consumed by other parts of the car, like the water pump or oil pump. Adding all of these upmeans a far fromperfectly efficient engine. The highest-efficiency ICE engine invented so far was a 90,000-horsepower diesel engine that was 52 percent efficient. In 2018, Toyota announced its new Dynamic Force Engine with 40 percent efficiency—twice the efficiency of any other engine on the consumer market. How did Toyota do it? The pistons inside the engine have been specially designed to have a very smooth surface—like a mirror—and that greatly reduces the friction of the piston against the engine cylinder. Toyota scientists also designed a high-efficiency fuel intake port so that more fuel could come into the engine. They also designed a better ignition system to convert more gasoline.

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