YOU might call it the bicycle pump way of designing cars - pick one model and then add air to make it bigger or let a little out for the next model down.

It's something the German car makers have been masters at for years; so that a BMW 5 Series shrinks to a 3 Series at 100 metres; an Audi A4 puffs itself up to an A6 if you squint.

And here is Volkswagen getting in on the design-by-pump trick with the Golf SV.

It's basically a modestly expanded standard Golf with dimensions that make it a bit bigger than the normal hatch and a little smaller than a Golf estate.

Now, most people will be happy with the untouched Golf hatchback, thinking it quite big enough inside and small enough on the road to make it worry-free in tight traffic spots.

But there are some - growing families probably - who will happily find the £975 it takes to add a bit of rear legroom, extra headroom all round and a bigger boot - which can be made larger still by sliding the rear seats forward.

Folding the rear seat down gives van-like stowage space while the front passenger seat can be folded flat to accommodate loads up to 2,484mm long (that's more than eight feet in old money).

So it's a versatile machine, well up to the unglamorous role of family minibus and, with prices starting at £19,225 not too big a drain on the family purse.

Move up to a SE spec like this one and you'll find goodies that include adaptive cruise control (fine for our crowded roads, where the car automatically keeps its distance from the vehicle in front) and city emergency braking, which stamps on the anchors at low speed if you don't notice the stopped car ahead.

Powering the Golf SV are a wide choice of petrol or diesel engines, with the 1.6-litre diesel in this car a popular choice. And no wonder; it pulls well enough on family duties and showed a useful 51mpg on the informative and clear trip display at the end of the test.

That already decent economy - and a distant growl from the engine at speed - might have been improved a bit if this SV had come with a six-speed gearbox. It's something now almost expected at this level, even if the engineers might say it's not needed.

What certainly is not needed in family transport like the Golf SV is suspension set up to tame Silverstone - and, thankfully, it doesn't get it. In fact, the car rode as well as anything in recent memory.

Optional (£765) satellite navigation was clear and easy to use, but twice failed to show any roads at all until the car had been restarted. Once, the windows and sunroof (a £995 option) unwound themselves a couple of inches, seemingly while the car was parked. Those couple of odd glitches apart, the Golf SV behaved itself impeccably.

With space, practicality and comfort high on the list of the SV's attributes there's no denying the car is a bit... unexciting.