The Mercedes GLS is big. Really big.

I manoeuvred into a space at my local supermarket’s car park, gathered my ‘bags for life’ and spotted a problem.

I couldn’t get out of the car. There wasn’t enough room to open the door.

It then necessitated several circuits of the car park to find a space on the end of a row. Granted, it required stepping into a flower bed, but at least I was out.

Something that was also rather concerning was how much of the front of the car was jutting out into the lane.

Such is life with the Mercedes GLS which is 5.21 metres long and just over 2.0 metres wide. Oh and double-check the overhead clearance because it stretches to 1.8 metres in height. You should also check the foundations of your driveway because it tips the scales at approaching 2.5 tonnes. Be careful in multi-storey car parks.

This is a sizeable piece of machinery, although it probably feels like a toy in Alabama, USA, where it’s built.

On the plus side, of course, there’s acres of room inside with carrying capacity for seven adults to ride in comfort. If you need to use the GLS as a load lugger, drop the seats and, well, you can clamber in and go for a walk.

This is a sizeable piece of machinery, although it probably feels like a toy in Alabama, USA, where it’s built.

Running boards are included with AMG trim on the GLS in the UK so, even though this is a tall car, access is surprisingly simple.

At the moment only two engines are available. The most popular is the one we tried, the Mercedes GLS 400d which uses a 3.0-litre, straight-six cylinder diesel engine.

There’s also a thumping AMG GLS 63 model which uses a 4.0-litre V8. The 400d range kicks off with AMG Line Premium trim for £75,610 rising to just over £92,000 for the fully loaded version.

If you want the full fat AMG GLS 63 model, prices start at an eye-watering £119,535. It’s just arrived in the UK.

Oh, and there’s a hybrid version in the pipeline which will include a 3.0-litre petrol engine.

Anyway, we spent a week in the company of the GLS 400d. No matter which trim you go for you’ll get all-wheel drive and a nine-speed automatic gearbox.

Air suspension is also standard. Granted, it does take a while to get used to the sheer size of the Mercedes GLS dimensions, but once you’ve got your bearings it’s actually quite simple to punt around tight streets.

This is largely due to the lofty driving position. You get a 360-degree camera as standard, which helps make for simple parking.

Don’t be fooled by the bulk. Apply the power, watch the bonnet rise and within 6.3 seconds you’ll reach 60mph. Unleash all of the horses and you’ll manage 148mph. These are impressive figures for such a sizeable machine. However, go easily, which is likely when you’ve got the family and Labrador on board, and you can top 35mpg.

You can also adjust the quality of ride by fiddling with the air suspension. After a quick play, we left it in comfort mode because it was the best compromise.

If you intend using your GLS for any driving on rough or slippery surfaces, you’d be advised to go for the off-road package which adds a low range gearbox, although the standard model will happily cope with rutted lanes, reversing a boat into a lake, towing a horsebox over a soggy field etc.

There’s a quality feel to the interior – and comfort is high on the agenda. All of the seats are supportive and electrically adjustable, and the front two rows are heated. You can even opt for a six-seater variant with two luxury individual seats in the second row.

The interior is very natty with plenty of gizmos. Mercedes pitches the GLS the S-Class of premium SUVs, after all.

You control most of everything in the car by selecting various screens and using a cursor to click on what you need. The only snag with this is that it’s tricky to keep your hand still while on the move.

If you need a sizeable SUV to carry seven people then it’s difficult to think of a better way to travel

The Audi or BMW selector wheel idea is much easier to use. There’s also a voice control system which generally works well and certainly has a bit of wow factor.

Apple CarPlay and Android Auto compatibility come as standard and, if you move up the trim range, you get semi-autonomous driver assistance systems.

To keep the kids happy, a pair of 11.6-inch touchscreens for films, music and internet enjoyment are attached to the backs of the two front seats.

If you need a sizeable SUV that offers the chance to carry seven people in unruffled comfort with all of their luggage, then it’s difficult to think of a better way to travel.

PS If you are using Eurotunnel, make sure you book for the single carriages. The twin deck carriages are too narrow. Eurotunnel’s advice is: ”If you’re booking online don't mention the make, model or registration because you might end up on a twin deck. Just select type and size, then high vehicle.”

OK, you end up being sat among buses and caravans but, hey, everyone gets there at the same time.

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