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Just a few years ago 'performance diesel' was a contradiction in terms, they were economical but about as exciting as E Coli poisoning. The diesel was the reserve of trucks, tractors and cheapskates; keen drivers would rather pull out their own toenails out than drive one. Cars like the BMW 335d will change all that.

The three-litre twin-turbo under the bonnet kicks out 282bhp, a respectable figure in itself, but then it's a veiled reference in this context, diesels live and die on torque - lots of it. The 335d comes with 428lb/ft, way more than the all-conquering M5 in a more compact and chuckable package. In fact this car has so much power that BMW couldn't fit a manual 'box, so the automatic is the only option. That and a limited rev range are the only downside of the car.

Even those that have absolutely no idea what torque is will appreciate just what it's doing for them with a prod of the right foot. This car can trundle along on tickover, and then a nudge on the loud pedal is all it takes to catapult it down the road. And that means in the real world, when we want to overtake, power away from a standstill, it's way better than the petrol-powered alternative.

It will hit 60mph in 6.1s and has to be limited to 155mph, as with all the high-power BMWs in accordance with the gentleman's agreement with Audi and Mercedes. But even that doesn't do justice to a car that will smoke its tyres from a standstill and pull like a train from anywhere. You need to wind a petrol engine up to the upper echelons of the rev counter to get the kind of performance that's available at tickover in this beast.

This car has a reservoir of pull just waiting to be tapped, with 95 per cent of the torque available from 1300 right through to 5000 revs, which took some clever technology to achieve. Almost every other twin-turbo has them side-by-side powering a selection of cylinders each: not this one.

In the three-litre BMW they're sequential, with a smaller turbo working at low revs and the bigger one kicking up further at the range. Towards the red line, a control valve vents some of the gas directly into the exhaust system. That means no lag whatsoever and as much power as you'll ever need from a car that returns 38mpg on the combined cycle and can cruise for hundreds of miles at a time.

And the real beauty of this, the most powerful six-pot diesel engine ever in a production car, is that none of this technical mumbo-jumbo will even cross your mind when behind the wheel. All the investment and innovation is there to convince you you're not driving a diesel at all. There's a slight rattle on start-up and the revs stay low, but there's none of the white smoke, juddering drive train and slug-like response that old-school diesel drivers will remember with a grimace.

The engine made its debut in the 5 Series and the diesel comfortably beat the 540i on track during an independent test thanks to its drag out of the bends. It's a deceptive kind of speed as there's no booming crescendo of revs that belong with the numbers on the clock, just a lazy 5000rpm on one counter, although the police would probably have been more interested in the triple digits on the other.

Left to its own devices the drivetrain shifts seamlessly up and down the six-speed box, but it comes with the steering-mounted shifter that genuinely works and feels just as strong as any semi-automatic on the market. It all adds up to a sporting feel that even today's diesels rarely manage, BMW has taken the fuel-sipping concept into a whole new arena and this is a car that will put a smile on the hardest driver's face.

The 3 Series is so intrinsically right when it comes to handling. It goes beyond the impeccable road-holding, it provides such a rich tapestry of its grip levels that the blind could follow the story. The suspension set-up squashes major ruts in the road and yet transmits every valuable nub of information, every change in the surface, with a gentle nudge on the wheel.

It's a confidence-inspiring machine that will have even average drivers pushing their personal limits and driving faster than they ever imagined they could or would.

Diesel blocks must be near unburstable, due to the extra pressure created by the more explosive fuel under the bonnet so the block is heavier. That means the 335i is slightly more nimble on the way into bends, but you'd have to be truly pushing the laws of Physics to feel that.

The BMW invited later and later braking and a healthy dose of power from the apex forward, and every exit of a junction was just another chance to blow a pound or two off the rear runflats' resale value as the Coupé followed an elegant arc, spitting stones at the scenery.

All it takes is a hefty dose of right foot, forcing the box to kick down, and audacious powerslides are there for the taking. The car mops up the excess enthusiasm and somehow comes through the bend at a ridiculous speed for a car with such a civil appearance. It's a sports car dressed as a minor executive's favoured transport.

The 3 Series is far and away Chris Bangle's most conservative creation, though, and it's almost as if the accountants stepped in with the volume seller, broke into his office at night and smoothed out a few of his famous edges. The flame-surface is still in full effect and the Coupe is certainly elegant enough, but it lacks a little visual impact and there should be a roaring trade in sports kits to butch it up a little. If you're swayed away from the borderline bland Audi and dreary C-Class, you should go the whole hog and tick the box for the M-Sport kit.

But the Coupe is certainly slicker and better looking than the saloon. Only the side indicator repeaters, rear badge and door handles were carried over on the exterior, everything else is new. It sits lower, looks ever so slightly meaner and much more streamlined. And the only downside is the loss of the middle seat in the rear, but two adults can fit comfortably in the back and most junior execs just don't have the time to make a big family these days.

So it's a hugely competent sports car wrapped up in a conservative body with an oil-burning powerplant under the bonnet. The days of the rattling diesel tractor are well and truly over.