Downsizing to a car with a smaller engine is being made easier by the latest turbochargers. They can transform a standard four-cylinder engine into a much more powerful motor Frugal four-cylinder engines used to be found only in the cheapest cars. But today they are being fitted to even luxury models. What has made them more acceptable indeed, desirable is the development of advanced turbochargers that cram more air than normal into the fixed volume of their cylinders, allowing the engines to burn proportionally more fuel. The result is a compact unit that punches way above its weight in terms of power and torque, a turning force which makes that power available at lower revs. These engines also provide better fuel economy and emit less pollution.