2013 Mercedes-Benz GL-ClassMercedes-Benz

If you thought the seven-seater Mercedes-Benz GL-Class couldn't get any larger, then you'll be in for a shock.

That's because the top-end luxury 4x4 has grown just a little bit bigger for 2013.

The new GL range is 21mm longer and 10mm taller than the series it replaces, and has a boot capacity increased by 60 litres.

The entry-level GL 350 BlueTEC AMG Sport costs from £59,465 when it goes on sale in January.

And new for this car is Intelligent Light System with bi-xenon headlamps and LED daytime running lights; AMG bodystyling; 21-inch AMG 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.

That's not forgetting the third row of seats being able to fold and rise electrically; two new metallic paint colours: Cavansite Blue and Cinnabar Red; Crosswind Assist; and Collision Prevention Assist.

However, despite the gains in size and equipment specification, the GL 350 is actually more economical and nicer to the environment. Fuel consumption is 15 per cent better – combined mpg is 35.3 mpg – and CO2 emissions are 14 per cent less at 209g/km.

The 2,987cc vehicle generates 258bhp and 620Nm of torque, and accelerates to 60mph in 7.6 seconds before achieving a top speed of 137mph.

Meanwhile the all-new GL 63 AMG starts at £91,680 and boasts flared wheel arches with 21-inch AMG alloys; better brakes; and an AMG sports exhaust system with two chromed twin tailpipes.

The 5,461cc GL 63 AMG generates 557bhp, a massive 760 Nm of torque, 288 g/km of CO2 and combined fuel consumption of 23mpg. It gets to 60mph in 4.9 seconds and reaches a top speed of 155mph.

Inside, GL 63 customers get an AMG Performance flat-bottomed steering wheel; AMG sports seats; and "luxury" automatic climate control.