This one's reckoned to be state of the art, yet when you start up it's not just obviously diesel, it's noisily obvious. And it's not just the sound, it's the association. The thrummy rumble when you floor it is pure black cab.
Actually the loudest thing about this BMW isn't the engine. It's the 'Velvet Blue' (aka purple) paintwork. There's more than enough of it on the outside, and then you slam the door shut behind you and aaaargh! More 'Velvet Blue' on the dash and centre console. Fortunately it's an option - the quite heroically naff sounding 'Youngline Interior' in case you're wondering which box not to tick.

Otherwise it's the usual Munich fare of sombre furnishings and peerless ergonomics. In some cars you can spend twenty minutes fiddling with various seat and wheel adjustments and not get comfortable. Jump into a Bee-Em, pull a couple of levers and it feels like it was designed around you, as though the designers crept into your bedchamber while you were sleeping and took a tape measure to your every dimension.

So what sort of animal is this particular Beemer? Badged 320td, it features a new 2-litre four-cylinder 'common rail' turbo-diesel also available in 3-series saloon and Touring, and it replaces the 318tds.

Not a car that's troubled us previously, the 318tds, so why are we devoting a page to its replacement? Well, peak power's up from 90 to 150bhp, and torque (the stuff that makes diesels worth a second look) swells from a fairly flaccid 140lb ft to a quite magnificently engorged 243lb ft. Which, as BMW points out with relish, is more than a Boxster S. The 0-62 time drops from 13.0 to 8.9sec.

And the figures really don't do it justice. Kick open the throttle in the intermediate gears at 2000rpm and it responds with such vigour that the average BMW driver might even feel compelled to put down his phone and concentrate on the road instead. Yes, it really is that fast.

Minuses? It doesn't spin as freely as a petrol engine, and the real action's restricted to a fairly narrow rev range (it's all over by 4000rpm). But keep it 'in the zone' and serious oomph is never more than a squeeze of the right foot away.

The five-speed manual gearbox has a light, easy action; in fact this one felt almost loose - you could wiggle the lever from side to side when it was in gear. But the major controls have that wonderful consistency of feel and weighting that's almost a BMW signature. The brake and throttle pedals are perfectly matched, both in position and weight, to make heel-and-toeing a cinch, while the steering has just enough meat and texture to keep a keen driver interested.

The chassis has no great sporting pretensions, with fairly modest looking 205/55s on 16in alloys and a supple ride that's just the right side of spongy. In fact it's extremely effective. That suppleness means you can keep up a rapid cross-country gait on less than smooth tarmac when drivers of more stiffly suspended cars would be forced to back off. It's nice to lean on the suspension and know there's more compliance, more travel to come if a mid-corner bump requires it.

There's plenty of grip to lean on too - you have to be almost medievally brutal to get a flicker from traction control in the dry. And that doesn't mean it feels inert; in fact it really flows from turn to turn.

The 320td's closest rival is the snappily titled Golf GT TDi PD 150. Similar concept, torque and performance, and more than two grand cheaper. But good though the VW is, I'd say the BMW is the more satisfying. And that's very good indeed.

'Performance diesel' might sound like an oxymoron, but they're here and you're going to see a lot more of them. Resistance is futile. And until they find a way of making it sound like a performance car, you can always console yourself with a combined fuel figure of 51.4mpg. Kind of sugars the pill.