Mercedes S63 AMG (2011)

The Mercedes S63 AMG has received the latest 5.5-litre twin-turbocharged V8 engine. In AMG terms that counts as a notable case of downsizing, replacing as it does the 6.3-litre naturally-aspirated V8 in the AMG line-up. But how does the smaller V8 affect the driving experience in AMG's hi-po limo?

Apparently popping two fives on the boot of the new 5.5-litre AMG S-Class would be a 'retrospective step', so the '63' badge remains. The engine swap alters the S63 significantly though. If you actually care what your £109,125 luxury sledgehammer saloon consumes it achieves 26.9mpg and 244g/km - helped by a start-stop system. Impressive, given the S63’s ample 536bhp and 590lb.ft of torque.
Spend a further £7,890 on the Performance Pack and an increase in boost from the 5.5-litre’s two turbos raises those numbers to 563bhp and 664lb.ft, dropping the 0-62mph time from 4.5- to 4.4 seconds. The speed limiter is raised from 155- to 186mph too.
The new S63 is an altogether more enjoyable driving experience than its rather incongruous, high-revving 6.2-litre V8 predecessor. With seven gears and peak torque available from 2,000-4,500rpm the S63 is effortlessly fast all the time - in the manner big luxury cars should be. Wring it out and it’s a maniac, a sort of Dr Jekyll and fine hides, with a rich cultured soundtrack in accompaniment.
AMG's tweaking of the Active Body Control imbues the big S-Class with agility combined with real comfort, though the S63’s size and lifeless steering eventually curb your enthusiasm. Nonetheless, the S63 handles remarkably well for a car of its generous proportions.

New safety kit debuts on the S63 too, with Lane Keeping Assist and Blindspot Assist intervening and braking individual wheels to keep you on course. It all adds up to a thoroughly accomplished autobahn-stormer. Just don't think too much about the bloke in the S350 CDI, who might not keep up with you in the fast lane, but will sail on by while you're stopped at the service station refueling your S63. The 26.9mpg claim requires resisting the temptation of that twin-turbo V8 to achieve.

• How much? £112,290.
• Engine: 5461cc V8 bi-turbo, 536bhp @ 5,500rpm, 590lb ft @ 2,000-4500rpm.
• Transmission: Seven-speed AMG MCT Speedshift, rear-wheel drive.
• Performance: 4.5 sec 0-62mph, top speed 155 mph (limited), 26.9mpg, 244g/km.