THE V8 diesel engine in the Mercedes-Benz GL420 CDI is a new-generation power plant.
This four-litre direct-injection unit, like the three-litre V6 engine in GL320 CDI, complies with the EU 4 emissions standard and features a maintenance-free filter to cut particulate emissions a further 99 per cent without using additives.
Twin turbos with variable nozzle turbines provide extra oomph - the GL420 CDI has a whopping 700 Newton-metres of torque. In the GL320 CDI, the maximum torque figure is 510 Nm.
But Mercedes says that fuel consumption and noise levels have been reduced, with the increase in power due mainly to a third-generation common-rail high-pressure injection system.
Both diesel variants are mated to the 7G-TRONIC seven-speed automatic transmission. Merc's accomplished gearbox offers the proverbial silky smooth performance and comes with Direct Select gearshift buttons behind the steering wheel for manual changes.
As a full-size seven-seater, the GL-Class offers outstanding interior space and comfort, plus all-wheel-drive.
From July 1, when the diesel special tax is cut, it might be the ultimate luxury car - only taller.
