Anybody who's ever had an electric car sneak up behind them knows that electric motors run a lot more quietly than internal combustion engines (ICEs). But with a beltless engine, even the ICE in a hybrid vehicle like the Prius can run more quietly. That's because there's no more squealing or buzzing from the belt. If you'd prefer that your car run as silently as possible so that you can listen to the radio or just contemplate the scenery in peace, beltless engines are a major step toward genuinely silent running. Now if only the car would drive itself, you could sit back and read a book in peace.