THE new generation Mercedes-Benz GL-Class will be the most advanced, high performance and fuel efficient version of the big 4x4 yet when it goes into production in January.

Two models will comprise a GL 350 BlueTEC AMG Sport and, for the first time, the GL 63 AMG with a whopping 557bhp of punch.

The former, which will cost from £59,465, is both longer and taller that the model it replaces and its boot capacity has been increased by 60 litres.

Economy and CO emissions have also both been improved, with a 15 per cent increase in combined fuel efficiency to 35.3mpg, and a 14 per cent reduction in CO emissions to 209g/km.

This 3.0-litre model generates 258bhp and can accelerate to 62mph in 7.9 seconds and on to a top speed of 137mph.

Standard kit now includes an Intelligent Light System with bi-xenon headlamps and LED daytime running lights, AMG body styling with 21-inch light-alloy wheels, privacy glass, an electric glass sunroof, AirMATIC air suspension, Parktronic with Active Park Assist and COMAND Online with media interface and DAB digital radio tuner.

You also get seven seats with an easy-entry system, the third row electrically folding and rising for better access.

Fresh comfort and safety features include Crosswind Assist, which works with the ESP sensor system to automatically intervene by braking to keep the car on course after a strong gust of crosswind.

And there's also Collision Prevention Assist, which gives the driver a visual and acoustic warning if the set safety distance from the vehicle ahead narrows, available for the first time.

Options include Parking Package with a 360 degree camera at £675, a panoramic sliding sunroof with interior sun blind for £920; On & Off-Road package, which gives the driver a choice of six programmes to adapt the vehicle configuration to the current surface at £1,985 and a Driving Assistance package that includes Active Blind Spot Assist, Active Lane-Keeping Assist and Distronic Plus with Pre-SafeBrake at £2,350.

The new GL 63 AMG model, which costs from £91,680, features enhanced kit like flared wheel arches with 21-inch titanium grey alloys, a high performance braking system, Active Curve System with AirMATIC - which compensates the roll angle of the vehicle body when driving round bends - and an AMG sports exhaust system with two chromed twin tailpipes.

The 5.5-litre model generates 557bhp plus a massive 760Nm of torque and can hit 62mph in just 4.9 seconds. Its combined fuel figure is 23.0mpg and it gives off 288g/km of CO

Inside, there's a flat-bottomed AMG Performance steering wheel trimmed in nappa leather, unique AMG heated sports seats with massage function and automatic climate control.