BMW 535i GT

This is a great answer – but what was the question?

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Let no market niche remain unfilled. Let no distinction be unblurred. Let no genre-defining name be safe. Meet BMW's new 5-series Gran Turismo.

First of all, here is what it is not:

A GT, in the accepted sense of sleek Gran Turismo, with a sloping fastback tail and space in the back for between nought and two children. (It has a fastback tail, but is hardly sleek.)

An SUV, despite its tallish stance and "semi-command driving position", suggesting incomplete control, not least because it lacks four-wheel drive. (The idea is to attract those who might like an SUV's loftiness but baulk at its connotations of aggression, planet damage, and over-specification for the tasks it is called upon to perform.).

A hatchback, despite having a hatch in its back. (To call it a hatchback, contends BMW, is to belittle both its size and the cleverness of its tail's creators.)

An MPV, despite some ingenious ways of using and hiding the rear seats. (MPV sounds too worthy and utilitarian, and the BMW is far too glamorous and luxurious for that.)

So, this is either a car which treads bold new ground, as Renault's Avantime (essentially a very plush Espace coupé) gamely tried to do with minimal success, or it is a car with a crisis of identity. First, though, that tail.

You saw it first in the Skoda Superb. The idea is that you can open either the lower half of the tail – as though a conventional boot lid – or the whole tailgate, including rear window, as one unit.

The BMW has a rigid rear shelf which attaches to spring-loaded boards behind the foldable rear seats, boards able to cover the gap between folded seats and boot floor. With the rear seats upright and slid to their rearmost position, the ensemble forms a box which acoustically isolates the boot space and makes for quiet travelling in the very spacious rear cabin. That's a part of the £41,150 GT's luxury ambience; another part is the fact that the interior design and finish is that of a slightly ritzier 7-series, BMW's biggest and most prestigious saloon.

The way the two-part tailgate works isn't quite the same as in the Skoda, though. That car defaults to the bootlid-only mode, and you have to press a button to make the two sections unite before you can open the entire tailgate. In the BMW, one button does boot, the other does the tailgate. Does that make it cleverer? Not really, because the BMW loses points for the bulk of the tailgate mechanism, and a rear window with so much black masking it's like looking through a letter box.

Fertile minds were, undoubtedly, exercised in this car's creation, but it's no beauty. Still, it's a BMW so it's likely to feel good on the road. Despite the 5-series tag, chosen to position the GT appropriately in the BMW hierarchy, it owes more to the 7-series under the skin as well as in its cabin. So, too, will next year's new 5-series saloon.

Three engines are offered to begin with, all with turbochargers: petrol fuels the 4.4-litre, 550i V8 and the new 3.0-litre straight-six in the 535i, while diesel feeds the also-straight-six 530d. All have an automatic gearbox whose eight gear ratios make it hard to remember where you are should you desire some manual intervention. It's better not to bother, and enjoy the engines' smoothness and impressive pulling ability. I tried the two "sixes", and the petrol one is outstanding, if thirstier.

This being an up-range BMW, various hi-tech options – such as unnecessary Active Steering which artificially hastens response at low speeds – can be applied to suspension already fitted with self-levelling air springs at the back and adaptive dampers all round. The latter can be set to Comfort, Normal, Sport and Sport Plus, with corresponding changes to steering weighting and accelerator eagerness. Helpful messages on a central screen describe the settings in case you didn't realise that the drive might be more comfortable or that maximum sportiness reduces stability (worrying, that one).

Underneath the technology overload, though, is a fine car with delightful engines, a smooth ride, and quite remarkable agility. It's a great solution. To what problem, I am not quite sure.

The Rivals...

Ford S-Max 2.5 Titanium: £24,895.

It's an MPV but with a powerful, five-cylinder engine and delightful driving dynamics. Few buy this, the fastest version, those who do love it.

Nissan Murano 3.5 Tekna: £32,150.

It's an SUV with concept-car looks and a great interior. The V6 engine is thirsty and you might not need the 4WD, but it's a pleasing machine.

Skoda Superb 3.6 Elegance 4x4: £26,885.

The Superb no-one buys owing to its extravagant innards, but stunning value next to the BMW. Beautifully finished, comfortable, clever.