There are 3.6-litre V6 or 4.8-litre V8 petrol engines, as well as a hybrid that uses a 3.0-litre engine with an electric motor, and a diesel - and none is short of pace. The V8 S and 4S are fast, but the performance is effortless rather than ballistic. The GTS has a slightly more powerful version, but the same is true. In the Turbo, acceleration is brutal - and the Turbo S is faster still. The diesel is usefully flexible, but with the V6 petrol, you're conscious of having to work it hard.