Mercedes AMG CL65

Never before has such a mighty unit been fitted to a production car. That's until AMG got to work on the 6.0-litre twin-turbo V12 in the CL Coupί¿½. Mercedes' tuning arm upped capacity from 5,513cc to 5,980cc and added bigger turbos and intercoolers. The brakes have been updated too, with eight-pot calipers and composite discs at the front.

Unfortunately, AMG hasn't done a lot else to the car, and it struggles to do justice to the masses of power from the engine. Inside, the walnut and leather cabin is at odds with the performance, and even the uprated brakes fail to impress, being over-servoed, squishy and still prone to fade under hard use.

The driver is totally reliant on the AMG's electronics to tame all that power, as feedback through the controls is virtually non-existent. Switch the computer-controlled air-suspension to Sport mode, and the CL65 never feels particularly taut. Still, you can use the performance to the full without reaching speeds that risk a prison sentence. The Merc covers the benchmark sprint from 0-60mph in less than 4.5 seconds, but the maximum speed is limited to 155mph, just as with cars which cost a fifth of the CL65's price.