BMW 520d Gran Turismo M Sport - First Drive

Engine: 2.0-litre four-cylinder turbo-charged diesel

Transmission: eight-speed automatic gearbox

Power: 184 PS

Torque: 380 Nm

Fuel consumption (combined cycle): 53.3 mpg

CO2 emissions: 139g/km

Top speed: 132 mph

Acceleration(0-62 mph): 8.9 seconds

Price: £39,905 (520d Gran Turismo from £35,705

Sometimes, a perfectly acceptable car struggles because it's aimed at the wrong sort of buyer.

One of the best examples was the short, cube-like and mostly unfairly-maligned Peugeot 1007, famous for its electric sliding side doors. Peugeot designed it for the young, urban and fashionable but anyone with elderly parents could see immediately that the 1007's sliding doors, huge side openings and high seating position made it perfect for less mobile geriatric motorists who sometimes struggle to get in and out of some of the more preposterously styled modern cars with their swoopy rooflines and heavily raked pillars. If Peugeot had pushed it through Saga, it might have had a hit on its hands.

A more recent example is the BMW 5-Series Gran Turismo, which went on sale in 2009, just before the current saloon and estate versions of the 5 were introduced. With its semi-MPV shape it offered lots of head and legroom, and its big talking point was supposed to be a hinged-in-the-middle bootlid-cum-tailgate. You can either open up the whole thing, like a tailgate on a hatchback or estate, or just the lower portion, leaving the rear window in place, like a saloon. Unfortunately, Skoda got there first with the second-generation Superb, so it was their clever tailgate that everyone ended up talking about rather than BMW's.

BMW seemed to be trying to position the 5 GT as some sort of glamorous lifestyley crossover for sophisticated continentals but professional drivers took one look at its space, quality and practicality, and thought “airport chauffeur car”. Only one thing stood between the 5 GT and its true vocation - its engine line-up, which consisted of powerful petrol and diesel straight sixes rather than fuel-sipping fours.

Now, though, BMW has finally bowed to the inevitable and produced a 520d version of the 5GT with a two-litre diesel engine - and it works rather well. The first thing to say is that the 520d doesn't really feel like the poor relation of the 5 GT range. It has the same spacious, luxurious cabin as the more expensive versions – it's one of the best around – with features such as leather upholstery and a full-length glass roof as standard. It even does pretty well out on the road, with the smaller engine providing plenty of go, thanks to generous torque and an effective eight-speed automatic gearbox. More impressive still; whereas BMW's diesel fours can feel quite rough in some other models, most notably the latest 3-Series, the one in the 520d GT is very refined, although enthusiasts will still miss the burbling engine note of the diesel and petrol sixes fitted to pricier versions.

Given that the 520d accounts for about 80% of all 5-Series saloon and estate sales, it always seemed a bit odd that there was no corresponding model in the 5 GT line-up. Now that anomaly has been corrected and you can expect the 520d GT to start turning up in large numbers in an airport drop-off lane near you pretty soon.