Power of up to 556bhp, torque of up to a frankly ridiculous 664lb.ft and fuel economy of 28.5mpg are some of the amazing numbers surrounding the newly announced Mercedes SL63 AMG.

As if that wasn't quite enough, 0-62mph is covered in as little as 4.2 seconds, the whole car is 125kg lighter than the old model and if it wasn't for the 155mph speed limiter, top speed would most likely be in the region of 200mph.

The SL (Sports Lightweight) has been getting rather heavy in recent years, so to increase both performance and fuel economy a huge chunk of weight has been cut out.

The bodyshell is all-aluminium, just like the SLS AMG's. That alone saves 110kg versus the previous model.

A remarkable balance of efficiency and performance has been achieved as a result. The 5.5-litre turbocharged V8 is the same as seen in other Mercedes cars over the last couple of years, but tuned for even more torque - more, in fact, than any other past or present car in this sector.

It will be available with all dials turned up to 11 via the optional AMG Performance Package, but as standard it's no slouch, posting a 0-62mph time of 4.3 seconds backed by 530bhp and 590lb.ft.

A new braking system has been devised to deal with this extra turn of speed. Two special-compound 390mm discs at the front are gripped by six-piston callipers, while 360mm rotors at the rear correspond with single-piston floating callipers.

All the luxury equipment buyers expect will still be present and correct, including two (regrettably optional) high-quality branded stereo systems from Harman Kardon and Bang & Olufsen.

As one of Mercedes' flagship convertibles, the SL63 will have every conceivable item of safety and security kit either installed as standard or available as extras, while other cost options include heated and chilled seats, lighter alloy wheels, upgraded leather and Active Parking Assist, which includes front and rear parking sensors.

Mercedes is staying tight-lipped on list price, but it's expected to be in the region of £110,000 before options.