We read much these days about the benefits of modern diesel engines.

We hear about the newfound quietness, the relaxed gait on the motorway and, of course, the parsimonious appetite for fuel.

It all sounds jolly lovely, but when the school has just rung to say your daughter has fallen over and should really go to hospital, you don’t want a relaxed cruise and, frankly, you don’t give much of a stuff about fuel economy either.

It actually happened this week. A nurse at the school rang to say my nine-year-old had had a “little” accident. Now in America that would mean she’d had a “little” accident but here, in understatement central, it could be anything from a damaged hairstyle to total decapitation.

What I wanted for the mercy dash was a V8 the size of an office block. But when news of my daughter’s “little” accident came through I ran out of the house to be presented, and there’s no other way of putting this, with a f****** diesel.

Much praise has been heaped on BMW’s 3 litre oil burner. It’s been described as refined and quiet and unusually powerful. Some say it’s actually better than BMW’s petrol engines.

Certainly I have no doubt that as paraffin stoves go it’s excellent, but can we be clear on something. Comparing it to anything fuelled with petrol is as stupid as comparing a typewriter to your computer. Yes, it’s more environmentally friendly. Yes, it’s cheaper to run. But you try downloading Gary Jules’s Mad World onto a Remington Atlantic.

They say that on a motorway it is not possible to say which fuel is being used. But that’s codswallop. It’s like saying you can’t tell whether you’re listening to a cassette or a CD.

Or whether you’re eating fresh or frozen fish. You just know . . .

And puh-lease can we stop trying to pretend that that the superior torque offered by a diesel engine in any way compensates for the lack of brake horsepower.

When you accelerate in a modern diesel there’s a satisfying surge, for sure, but it’s over in a moment. And there’s no power to carry the momentum. Time and time again I put my foot down in that Beemer, pulled out to overtake the Rover, and then when I was on the wrong side of the road simply ran out of oomph.

A petrol engine will spin happily, in some cases to 8,000 or 9,000 revs per minute. The BMW diesel is revvier than most but it’s all out of ideas at just 5,000.

Of course, even when you drive like you’re on fire, it will refuse to do less than 40mpg and that makes for massive savings at the pumps. I’m talking about halving your fuel bills. But if saving money is so important why not go the whole hog and use the bus? A diesel would work in a car that’s not supposed to be fun, a big 4x4 for instance or a small Volkswagen. But in a BMW, or a Jaguar for that matter, it’s daft.

These cars are supposed to be all about poise and balance and delicacy. They’re supposed to be the ultimate driving machines and they’re just not when you have a coal-fired power station under the bonnet. If you just want cheapness why not save even more money and buy a Mondeo? Still, let’s leave the absurd and ridiculous engine out of the equation shall we. Assume you’ll buy a petrol version and have a look at the rest of this remarkable car.

The new 5-series is very possibly the most talked about new car of the year. Chiefly this is because the old one was just so utterly fabulous, easily the best car in its class when it came along seven years ago and, astonishingly, still the leader when they pulled the plug seven years later.

You didn’t have to think when you were looking for a £30,000 four-door saloon. You bought the Beemer and you loved it. But you do have to think with the new one, because the styling is, how can I put this, a bit challenging.

I’m told that as time passes we will become accustomed to the looks, which manage to be sharp and bulbous at the same time. But that’s like asking a seven-year-old to live on olives because he’ll like them when he’s an adult. In the here and now the 5 is truly gargollic, a symphony of discords and stylistic infighting. ()

And it’s no better on the inside, with acres of extraordinarily cheap-looking plastic moulded into a series of shapes that jar.

This then is going to be one of the trickiest road tests I’ve ever done. Because I’ve got to ignore the engine and the styling. And the views of my children, who claimed it made them feel sick because they couldn’t see out. Even my wife didn’t like it because she can’t understand why anyone chooses to buy a BMW and then doesn’t go for the M3.

Surprisingly, the new 5 is not that far removed under the skin from the old one. They have the same multilink rear axle and the same quasi MacPherson strut arrangement at the front. And both use electronics in the shape of stability and traction control instead of mechanicals like a limited slip diff.

The only real difference is weight. Although the new version is a couple of inches longer and comes with more kit as standard, it’s 65kg lighter. So it should be more nimble than the old one.

It isn’t, though. The balance is still there and the poise, and the ride is exceptionally good for a car which handles and grips so well. In these respects it’s still far, far better than any Audi, Jaguar or Mercedes. But the steering is odd.

It’s fine when you’re moving at a lick but it’s devoid of feel at low speed. Maybe it’d be worth buying the new £800 active system, which changes the amount of wheel-twirling you have to do as the speed builds. So, at 10mph, a quarter of a turn of the steering wheel moves the front wheels as much as a whole turn does at 100. It works well.

The trouble is that this is just one of about 1,000 extras that can be fitted. There are seven different types of wheel, eight different types of front seat, endless stereos and a trim selection that puts the Farrow & Ball colour chart to shame. Mercedes, it must be said, doesn’t give you enough choice when buying a car — “you vill have ze grey” — but it could be argued BMW gives you too much.

If you go for the standard car it’s pretty well equipped anyway and costs £30,950. But you won’t, because you’ll buy the 530 petrol which is just £5 more.

Or will you? Yes, the new 5-series is unpleasant to behold and yes, its steering is a bit weird, but what else can you buy for this sort of dosh? You can’t have a Mercedes because it’ll break down all the time and the dealer won’t be able to fix it. The Audi A6 is on its last legs. The Saab 9-5 is mad. The Lexus is dull. You won’t pay £30,000 for a Volkswagen. And I’m sorry but if you’re worried about aesthetics you’re hardly likely to go for an S-type Jaguar.

The BMW, then, is still out in front. But only because all the other cars are so far behind.

Footnote

I wonder what would have happened had I been caught speeding on my way to the hospital in the 5-series.

Had it been by one of the two speed cameras I drove past, I fear no amount of pleading would have worked. You can’t argue with a box.

Whereas if we had real policing on the road, I feel sure Plod would have been understanding. It’s a small point, but one which is rarely raised in the speed camera debate.

My daughter incidentally turned out to be suffering from a small bruise. And a large dose of hypochondria.

VITAL STATISTICS

Model BMW 530d SE
Engine type Six-cylinder, 2993cc diesel
Power 218bhp @ 4000rpm
Torque 368 lb ft @ 2000rpm
Transmission Six-speed manual, rear-wheel drive
Suspension (front) spring strut axle with double-joint thrust rod (rear) aluminium multilink
Fuel 40.9mpg (combined)
Acceleration 0 to 62mph: 7.1sec
Top speed 152mph
Price £30,950
Verdict Gargoyle-like in appearance, but still ahead of the competition

Explore Jeremy Clarkson

• Greatest Hits

• Good Car, Bad Car