Motoring review: Audi A3 Sportback 2.0 TDI Sport

Price: £22,705 (range starts at £19,825)
Engine capacity: 2.0-litre turbo diesel
Power output (PS @ rpm): 150 @ 3,500-4,000
Top speed (mph): 134
0-62 mph (seconds): 8.7
Fuel economy (mpg): 67.3
CO2 emissions (g/km): 108

If the new Audi A3 looks familiar that's because it's not that different from the old Audi A3. That's not necessarily a bad thing, though. A quick browse of the firm's website suggests Audi sells 44 different types of car that bear the Four Rings. And of all of them – from sleek supercars and off-roaders to luxury saloon and estates – the A3 is the company's best-selling car in Britain, shifting 25,000 models a year.

The new model follows the standard identikit Audi design formula from Ingolstaft. That doesn't mean it's unattractive, though, and in this Sportback form it has escaped the crowded Audi stable with five doors and an extra 58mm in length over the standard A3. That might not sound like a lot but it creates an extra chunk of legroom in the rear – enough for adults to sit comfortably. The boot is also bigger, making the Sportback a properly practical car. It is also what luxury car-makers call a "premium compact" so inside there's a host of chrome dials and soft-to-touch surfaces.

Sales will be primarily split between the 148bhp 2-litre diesel and the 120bhp 1.4-litre petrol unit. There's a £2,300 premium for the oil burner I'm testing which will, on the motorway, cruise along in near silence, all while giving you an mpg figure many so-called green cars would be proud of. It's low on the tax front too. Though it's no sports car, it is a rapid motorway cruiser and can be thown around on B roads with ease. The odd thing is that I feel like I've driven this exact car before.

I haven't, but I drove the new VW Golf recently. And it's under the skin of the new A3 Sportback where things get interesting. It uses the Volkswagen Group's new Modularer Querbaukasten (MQB). That's German for modular transverse matrix to you, and it's the firm's new "mega platform". Bear with me here. I know it's not exactly a Virgin Galactic rocket test but it is revolutionising the way VW Group does business and is well on the way to making it the biggest car-maker on earth. Let me explain; Volkswagen Group is made up of 12 car companies, including Audi, VW (there's that Golf, you see), Seat, Porsche and Skoda, and by using this sort of Lego-style underpinning it can base many different types, sizes and brands of car on the same platform with huge savings.

This has been the automotive Holy Grail since the days of the Model T as car-makers have dreamt of building the same basic car which they car tune and subtly alter on top (and in their engine offerings) to sell across the world in different markets. It's not cheap, though, and the MQB is thought to have cost the VW Group somewhere in the region of $70bn. In return the potential pay-off is huge: Morgan Stanley estimates savings of $19bn for the firm by 2019.

Along with the Seat Leon, Skoda Octavia and VW Golf the Audi A3 is one of the first of dozens of new models. And here's the rub – if you spend £22k on an A3 Sportback it has the same basic underpinning underneath as a £17k Seat Leon or VW Golf. Should you feel short-changed? Not really. You might be thinking "hang on a minute, why should I splash out for the Audi?" but you'd be missing the point. All three cars are good but they are aimed at different types of buyers; the Audi, for example, is about the badge, cosseted ride and higher levels of luxury.

Yes, I suppose it's true that modern cars are all getting similar in some respects and that's probably a little boring, but it's not necessarily always a bad thing.