It took me a while to figure out what was so different about this new BMW 7-series, because it was just about the last thing I’d been expecting. BMW, the company that wears its technology not so much on its sleeve as tattooed on its forehead, has made a car with a rather old-fashioned feel to it, and this is no bad thing.

I’ve never tried to hide my dislike of this car’s predecessor, which I found to be ugly and uncomfortable. It pioneered BMW’s iDrive system, which is unfathomably complex in operation and needlessly confusing in its presentation of information. I recall once pressing a button and watching a keyboard emerge from the fascia.

I’m glad to report that this new 7-series, particularly the £54,160 entry level 730d that most 7-series customers will buy, is not similarly afflicted. Although it has more technology than ever, it is kept where it should be — behind the scenes. The car looks as unremarkable in the flesh as it does in these pictures, and while that might be a criticism, were this a new Audi, after the awkward styling of the last 7-series, it’s a welcome development.

This new simplicity is also to be found in the car’s interior. The switchgear has a simpler layout, and while the iDrive controller is still there, so too, mercifully, are individual buttons for calling up whichever menu you want to explore.

Fire up the 3 litre 245bhp diesel engine and you’ll discover it sounds just like the big old six-cylinder petrol motors you used to find in BMW saloons of the 1970s and 1980s. It’s a bit gruff, but in these days of turbine-smooth powerplants, it’s also refreshingly characterful.

And it really gets the job done: board members can demonstrate to their shareholders that their new limo uses less fuel and produces less CO2 (39.2mpg and 192g/km respectively) than a 2.3 litre Ford Mondeo. Then they can climb aboard and, with the saintly look still on their faces, charge to 62mph in 7.2sec and go on to 153mph. For a car weighing almost two tonnes, this is an astonishing blend of performance and economy.

Yet, despite all this wonderfully good work, I still have fundamental reservations about this car. The main role of a luxury car is to be luxurious, and given that every 7-series rival also comes dripping in wood and leather fittings, it is ride comfort and refinement — the twin pillars upon which all luxury cars stand or fall — that can make the difference. Unfortunately, in neither of these spheres was the 730d as good as I had hoped.

Like every other 7-series I’ve driven in the past 20 years, its ride is too firm to be called truly luxurious, and on certain coarser surfaces there’s an unwelcome amount of tyre noise. BMW has always tried to position its flagship as a sporty drive, which could explain why the Mercedes S-class has always outsold it. A dynamic driving experience is one thing, but trading a feeling of luxury as a result is truly counterproductive.

The 7-series not only has its class duties to consider, but also company brand values to maintain. It must, therefore, fit into a range befitting BMW’s “sheer driving pleasure” slogan. Fortunately, it does: the 730d is notably good to drive for a car so big and heavy: it steers crisply, holds the road well, even in slippery corners, and seems to shrink around you so that, after a little acclimatisation, it feels little bigger than a 5-series.

I wish I could say the same about the other 7-series that BMW let me drive — the long-wheelbase 750Li, which, at £69,400, sits at the opposite end of the range. This model was fitted with almost every optional piece of trickery in BMW’s considerable electronic armoury, including steering that acts on the rear wheels as well as the front.

It had active anti-roll bars that near enough eliminate body roll, side-view cameras for parking, and a thermal-imaging night-view camera that can identify pedestrians lurking in the gloom. I drove it only during the day, so I couldn’t test the effectiveness of the thermal imaging, but the only piece of technology I would not do without is the camera that reads road signs and keeps you constantly abreast of the prevailing speed limit. The rest failed to make the 750Li feel anything other than a cumbersome, less appealing car than the entry-level 730d.

Clearly, this is not a great time to be launching a two-tonne limousine, but in the 730d, BMW has a car that deserves to take its fair share of the meagre supply of customers for cars of this ilk. It is the most frugal full-sized luxury car on sale, and it has the lowest emissions. It’s good fun to drive and has more than enough space and luxury appointments inside. Were it not for the issues surrounding its ride comfort, it would be a wholly convincing match for the more comfortable and hushed Mercedes S 320 CDI. Unfortunately for BMW, however, in cars such as these, that is still what matters most.

BMW 730d SE

ENGINE 2993cc, six cylinders

POWER 245bhp @ 4000rpm

TORQUE 398lb ft @1750rpm

TRANSMISSION Six-speed automatic

FUEL/CO2 39.2mpg / 192g/km

ACCELERATION 0-62mph: 7.2sec

TOP SPEED 153mph

PRICE £54,160

TAX BAND F (£210 a year)

VERDICT The best 7-series yet

RELEASE DATE Yesterday

ALSO WORTH CONSIDERING

Mercedes-Benz S 320 CDI £55,885

For: World-class ride and refinement, spacious interior

Against: Odd looks, quite pricey

Audi A8 3.0 TDI quattro SE £51,995

For: Looks great, terrific cabin ambience, good value

Against: Poor ride quality, no fun to drive