8 cool things cars of the future will do

Gas-powered engines are far more efficient than they've ever been. But even as electric cars seem nearly ready to replace gas engines, engineers are still finding ways to squeeze more from the 150-year-old technology.

Many automakers have been trying to perfect what's known as Homogenous Charge Compression Ignition -- a way of making gasoline engines behave like their efficient cousins, diesel engines.

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Mazda engineers have designed one that uses air compression and is 30% more efficient. Although diesel engines ignite fuel without a spark plug, Mazda's effort -- due out in 2019 -- sometimes uses one. That's because it's not always most efficient to use a compression ignition. Mazda's engine works whichever way is best given the situation at any moment.

Meanwhile, engineers with Nissan's luxury division Infiniti have developed an engine with variable compression by giving the piston, which compresses the air, variable range of movement.

When combined with turbocharging, which uses small turbines to force more air into the engine, it promises super-fast performance with better fuel economy.