• Diesel the best performer for fuel consumption
• Petrols are very thirsty
• Unlikely to be cheap to maintain

What are the running costs?

If you don’t want your GLS to be ruinously expensive to run, then stick with the diesel-drinking GLS 400 d. Officially it’s capable of low-30s, although we managed mid to high-twenties with a fair bit of town driving. Stick to the motorway and it should peek above 30, but an X7 is a more efficient option if you stick to six-cylinders.

At the opposite end of the scale are the AMG and Maybach models, both powered by a 4.0-litre petrol engine. Thanks to being (a little) lighter, the more powerful AMG GLS 63 is ever so slightly more economical at around 22mpg, compared with the Maybach GLS 600’s claim of just over 21mpg.

21

Such differences are nuanced and in the real-world, because the AMG encourages you to drive harder, it’s likely to be the champion guzzler. Don’t expect either to achieve above 20mpg with any great frequency, though. All GLS models emit well over 200g/km, with the V8 versions hovering around 300g/km. Not only are all very expensive for first year VED car tax, they all slot into the 37% bracket for Benefit-in-Kind (BiK) company car tax. You’ll need to look towards the plug-in hybrid Range Rover or Bentley Bentayga to pay less unless you go fully electric.

21

Servicing and warranty

The GLS is covered by Mercedes’ standard three-year/60,000-mile warranty if anything goes wrong. This can be extended for a fee.

Running costs for the GLS will also be expensive, not least servicing, tyres – the minimum wheel size is 22 inches, don’t forget – and similarly brakes, particularly for the AMG models. This is not a car that can be run on a budget and trying to do so will only harm the Mercedes and its resale value.

Reliability

This latest GLS is all-new however, with new components shared with the GLE SUV. There are a lot of systems to go wrong, but it all feels solidly put together and would have been tested thoroughly to put up with the rigours of life as a luxury SUV. Indeed, there have been no recalls on the current version.