Mercedes-Benz S-Class

AMG's normally aspirated 6.2-litre V8 makes a noise akin to the Viking hordes on their way to Valhalla. It's one of the all-time greats, so I have to admit I approached its replacement, an all-new 5.5-litre twin-turbo V8 given its debut outing in the (confusingly badged) S63, with a degree of scepticism.

Especially as this is AMG going ‘green'. Really? New boss Ola Källenius has introduced something called AMG Performance 2015, and claims that the firm's aim is ‘to continually reduce the fuel consumption and emissions of new models... while enhancing the core brand value of performance.' The new unit is accordingly 25 per cent more fuel efficient (26.9mpg), and chucks out 30 per cent less CO2 (an amazing 244g/km), while still packing 537bhp and thundering to 62mph in 4.4secs and a top speed of, oh, a million miles per hour.

How? By reducing capacity from 6,208cc to 5,461cc, adding a pair of turbochargers, using spray-guided combustion, piezo-electric injectors, fitting an aluminium crank-case, and introducing four-valve technology with adjustable camshafts and an air-to-water intercooler. AMG's ‘controlled efficiency' programme also sees the fitment of smart generator management which uses kinetic energy to charge the battery, as well as the dreaded stop/start system. In this installation, s/s registers the resting position of all eight pistons and restarts the engine by injecting fuel into the combustion chamber of the cylinder with the best piston position. Clever, but I still don't like it. In ‘S' (sport) or ‘M' (manual) mode, s/s is always off. It's for the best, really.

AMG's seven-speed multi-clutch transmission is mated to the new engine for the first time. It uses a wet clutch to reduce frictional losses, and in ‘C' mode pops you immediately into seventh gear for maximum efficiency. With 590lb ft of torque between 2,000 and 4,500rpm, it'll happily sit there all day, but naturally it does its best work in ‘M' mode in conjunction with a heavier right foot. Like the supercharged version of Jaguar's exquisite XJ, you simply won't believe just how fast and accurately you can hustle a mega limo. It gets no better than this.

Unless, that is, you happen to have the S63 Performance Pack. This whacks the turbo's charge pressure up to 1.3 bar, boosts power to almost 570bhp and torque to 664lb ft, and hoists the top speed to 186mph. It's £8k more, but at this stratospheric level, you'd be silly not to.
What next for AMG? On its current form, we can't wait to find out.

Jason Barlow

On your drive for: £2,713pcm
Performance: 0-62mph in 4.5secs, max speed 155mph, 26.9mpg
Tech: 5461cc V8, RWD, 537bhp, 590lb ft, n/a kg, 244g/km CO2