What is it?
It’s Mercedes’ 451bhp C 63 AMG, with a bit extra. AMG’s Performance Pack doesn’t actually turn up the sensational V8’s volume at all, though; the extras are all added elsewhere.
For £3210 you get new springs (10 per cent stiffer), composite brakes, aluminium trim, a leather/Alcantara steering wheel and, most notably, a locking rear differential.
What’s it like?
Well, the rear diff and springs do a great job, endowing the C 63 with levels of traction and lateral grip that regular AMG pilots may not be accustomed to.
You will have to try very hard to unstick the C 63, and even if you do, the diff will make sure that things have progressively enough for you to cope. The brakes have terrific stopping power, too, and decent pedal feel.
The best bits of the C-class’s cabin remain, including fantastic bucket seats, and the AMG steering wheel is a delight to hold.
Now, the downsides: the diff is a tad noisy (its whine becomes intrusive after a while) and the trade-off for that rigid chassis is a ride that borders on uncomfortable; it tramlines a bit, too.
Our test car was fitted with optional 19in wheels, though, so we’d ask for a test drive on 18-inchers before dismissing the suspension.