New York motor show 2012: Mercedes unveils SL65 AMG

Mercedes-Benz has followed up the unveiling of the new SL63 AMG with a first look at its big brother, the mighty Mercedes-Benz SL65 AMG at the New York motor show.

The new range topping SL model adopts the aluminium body shell and other weight saving measures of its lesser-engined siblings in a move that has seen its kerb weight slashed by a considerable 170kg to 1950kg.

Under the bonnet resides a mildly reworked version of the old SL65 AMG’s potent twin-turbocharged 6.0-litre V12 engine boasting changes to its inlet and exhaust systems. Power climbs from a previous 603bhp to 621bhp on a band of revs between 4800 and 5400rpm, endowing the plush new two seat roadster with a power to weight ratio of 318bhp per tonne. Torque remains limited to 737lb ft between 2300 and 4300rpm.

Altogether, this represents a 91bhp and 111lb ft increase over the new twin-turbocharged 5.5-litre V8 powered SL63 AMG, or 64bhp and 73lb ft over the SL63 AMG running the optional Performance Package – something that is not offered on the SL65 AMG.

The revised V12 engine, which goes under the internal codename M279, drives the rear wheels via Mercedes-Benz’s 7G-Tronic seven speed automatic gearbox with a raft of BlueEfficiency features including automatic stop start rather than the two decade old 5G-Tronic used by the old SL65 AMG.

As a result fuel economy has been boosted by 17 per cent at a claimed 24.4mpg while CO2 emissions drop to 270g/km. Standing start performance is increased incrementally, Mercedes-Benz’s AMG division claiming 0-62mph time of just 4.0sec – 0.3sec inside the time quoted for the SL63. Top speed remains limited to 155mph.