Road Test: Mercedes-Benz GL Class GL320 CDI 5dr Tip Auto

There's a contradiction here. The Mercedes GL is a vast, costly and showy thing; the sort of car that attracts equal measures of envy and contempt from a deeply divided society. But an entry-level diesel version doesn't seem to fit with anyone's preconception of what this hugely vulgar SUV is all about.

The industry pundits forecast that the GL320 CDI - yours for a mere £51,675 - will be the volume seller in the UK. And given that it is £11,400 cheaper than the next model up, they might be right.

But this is a car that's unavoidably ostentatious, a status symbol for that blinkered minority hanging onto the contemptuous notion that bigger is better, that size means security. And people who like this sort of thing are going to find the extra money for the 5.5-litre V8 petrol version, with more power, torque and refinement.

Meanwhile, people who hate it aren't going to forgive you for buying the £50k diesel version, either. In their eyes that'd be like forgiving an axe-murderer because he gave the crime scene a quick wipe on his way out.

It's worth having a look at just what the GL has to offer in any variant first. Seven seats for a start. But a Land Rover Discovery has that and it's very nearly half the price of the cheapest GL. It's quite luxurious inside too, but it's definitely not on a par with Merc's saloons in this respect, despite being almost as expensive as the equivalent S-Class.

Off-road capability is also right up there with the best of them, but they've just banned that almost everywhere in Britain, and are you really going to hammer your £50k bling-bling SUV up a rocky track anyway? Answer: no.

As for that diesel lump, it is a very good one. Mated to Merc's tidy seven-speed auto 'box, the delivery is smooth and linear and the GL feels fairly rapid despite 2.5 tonnes of bulk.

The three-litre V6 sounds rougher than it does in something like the CLS, though, maybe because it has a lot more work to do with no extra power, but it's impressively refined for a massive diesel SUV.

Economy isn't bad at 28.2mpg either, but that's still not enough to silence the environmentalists or make the dickheads amongst us forgo the thirstier, flashier petrol option. The GL is something you either love or hate with no middle ground.

Which means there's nowhere for the GL320 CDI to park. All 5.2 metres of it.