10 October

You need air to burn things, and turbos provide a lot of extra air, by sucking it out of the exhaust and back into the engine. They don’t make a petrol or diesel much more efficient (you might get to 40-50% efficiency at best), but they do allow you to use a smaller engine to get the same power, which is where any fuel savings come from. It still makes turbos much less efficient than any electric motor, which runs at over 90% efficiency, and which gives instant power and torque. It doesn’t need air, it’s not burning anything.