BMW head-turner; motors-midlands.

Byline: By Edward Stephens MOTORING EDITOR

THERE is nothing like a sleek convertible to turn heads.

But most four seater drop tops are nothing like a sleek convertible.

BMW, however, with its 635d has a four-seater which is every bit as streamlined as any two seater sports car.

The success is partly due to the fact that the BMW 6-series convertible doesn't really look like a car which will seat four adults in comfort.

From the outside this stylish soft top has all the appearance of a long. low two-seater, with a distinctive shark-like nose.

An elegant and beautifully appointed cabin has soft leather seats - cream in the case of my test car - with dark birch wood detailing on the dashboard and a plethora of gadgets and gismos for the hi-tech man or woman to play with.

BMW says this car, and its sister Coupe model, are the world's first diesel-powered luxury 2+2 Grand Tourers.

Apart from the driving controls on the 635d almost everything else - entertainment, climate, navigation and communication - is controlled by one large dial in the centre console, the iDrive.

Having turned the dial to any one of the four functions you can then lock it in and make any adjustments you want. It does help keep the dashboard clear of numerous switches although I couldn't help thinking that to simply change the radio channel it is far simpler just to press button 1-6 on the radio, and at least your eyes are back on the road much quicker.

When the sun comes out the hood on the 635d can be lowered in seconds at the touch of a button and disappears completely into the boot area. Even with it lowered, however, there is still an impressive amount of space in the boot.

When the hood is up you can create more luggage space by reducing the size of the compartment that houses it in the boot area with a simple lever action - and that gives you room for the largest of suitcases.

Unusually after lowering the hood the independent glass rear window pops up again and forms a useful wind deflector. If there are only two people in the car, however, you can lock into place an even more effective centrally located wind deflector.

My test car was powered by BMW's superb 3.0-litre diesel engine mated to a six speed auto box which also featured paddles on the steering wheel for Formula 1-style gearchanges.

Arguably the best big diesel around this unit offers tremendous acceleration and blistering mid-range pulling power.

At the same time it's quiet and - for a big engine - very economical. Covering more than 400 miles in a week I averaged just over 37 miles per gallon.

For a more sporting drive you can depress the Sport button near the gear shift to bring the Dynamic Driving Control system into play to give you even quicker gear changes, make the engine and the steering more responsive and eliminate the use of sixth gear.

The engine uses twin turbochargers, the smaller one operating at low engine speeds and a larger unit working at higher speeds to give your superb flexibility, refinement and power.

In fact after a few days with the 635d you begin to take the smoothness of this sixth cylinder engine for granted. It wasn't until I came to drive a large four cylinder diesel engine car - also with an auto box - immediately afterwards that the quality of what I had just driven really came home to me.

The 635 is not a cheap car by any standards but it's a car that for me ticked all the right boxes.

It's a great looker, it offers a high performance sporting drive, it's refined, beautifully appointed inside and out, offers topless motoring and is economical.

Can there possibly be more boxes that need ticking?

Fast Facts

BMW 635d Sport

Convertible Price: pounds 62,395.00

Mechanical: 286 bhp, 3,000cc, 6cyl diesel engine driving front wheels via 6spd automatic gearbox.

Max speed: 155mph

0-60mph: 6.6 secs

Combined mpg: 39.2

Insurance group: 20

CO2 emissions: 190g/ km

Warranty: 3 years/ unlimited; 3yrs paint; 12yrs anti-rust.

CAPTION(S):

BMW's 6-series convertible in action