The car's upgrades are part of efforts to provide the big SUV with greater levels of luxury in a bid to see it more closely challenge the likes of the Range Rover and upcoming Bentley Bentayga.
The standard engine line-up includes both carry-over and upgraded petrol and diesel units. Each provides improved fuel economy and reduced CO2 emissions due to the adoption of a new nine-speed automatic gearbox in place of the older seven-speed unit used by the outgoing GL.
On the petrol side (but not available in the UK) is a twin-turbocharged 3.0-litre V6 developing 328bhp in the GLS400 4Matic, and a twin-turbocharged 4.7-litre V8 in the GLS500 4Matic that produces 449bhp (an increase of 20bhp over its predecessor). The 3.0-litre V6's official claimed combined economy figure is 31.7mpg and CO2 emissions are 306g/km – an improvement of 2.3mpg and 19g/km on the old GL400 4Matic.
As before, there is a single diesel in the form of a turbocharged 3.0-litre V6. It continues to produce 187bhp in the GLS350d 4Matic, although there won't be any official economy and emissions claims until closer to its launch in the UK in early 2016.
The top engine is an AMG-produced, twin-turbocharged 5.5-litre V8 in the GLS63 4Matic. It delivers 577bhp - 27bhp more than its predecessor - and 560lb ft, as it did before. Unlike the standard engines, it continues to be mated to an updated version of AMG’s seven-speed, Speedshift automatic gearbox.
A petrol-electric plug-in hybrid model is also a possibility but hasn't been confirmed for production.
Buyers can specify the GLS with an upgraded Dynamic Select system that offers up to six driving programs including Comfort, Slippery, Sport, Individual, Off-road and, in models equipped with the off-road package, Off-road Plus. This last mode activates the low-range gearing and centre differential, as well raising the ride height to provide 306mm of ground clearance, along with a fording depth of 600mm.
Further changes are centred on the GLS’s standard Airmatic air suspension. It receives updated three-chamber dampers that are claimed to provide improved self-levelling properties for a more comfortable ride.
As with the older GL, buyers can also specify a so-called Active Curve System. This uses hydraulically operated anti-roll bars to reduce body roll during cornering and improve straight-line stability.
Pricing for the new GLS starts at £69,100 for the 350d AMG rising to £78,095 for the 350d designo Line edition. The range-topping GLS 63 AMG costs £102,330.
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