What Car? says...

On the face of it, the Audi S5 looks like a stylish and suitably sporty coupé. But if you’re imagining a bone-shaking ride and an engine that drinks fuel faster than a Formula One car, then prepare yourself for a pleasant surprise.

You see, unlike the range-topping RS5 model, which is all about performance, the S5 is a surprisingly easygoing companion that has a diesel engine capable of averaging more than 40mpg. It’s still very fast, mind.