BMW is quite honest as to why it has abandoned a soft top on its new Z4 Roadster in favour of a folding two-piece metal hardtop – it was losing sales to the Mercedes-Benz SLK.

BMW marketers asked existing and potential BMW customers what they wanted from a new Z4.

They were quite emphatic – a car that offered security, safety and style, one that was more practical with a more forgiving ride, a larger cockpit and yes, a folding hardtop like the Mercedes SLK.

That irked BMW because no one likes losing sales to a competitor. So this new model’s job is to capture sales not only from Mercedes, but also Audi (which has retained soft tops) and Porsche.

To do this the engineers and designers had plenty of work to do. It is not easy for the engineers to meet the demands of the marketing men and their contradictory demands for a sports car that mustn’t be too sporty!

But they have done it. They have come up with an excellent Z4 replacement that really is great to drive, has an excellent choice of engines and is additionally £800 cheaper than the Merc SLK

It is also longer and wider than the outgoing model, making it that much more comfortable and practical.

And of course there is the metal folding roof that will nip up or down in a quick 20 seconds. Yes it does take up some of the boot space when lowered, but there is still enough room for overnight bags etc.

The engineers have also come up with a new acronym – DDC or Dynamic Drive Control with three settings – Normal, Sport and Sport+ The lowest is for more comfort, the middle one for good all round performance and the third is akin to the old car’s base set up.

Personally I found Sport to be the best setting. It controls not only the suspension but also throttle response, gear-change time and steering to your liking.

On the press launch of the car in northern Scotland I soon found that the ‘sport’ setting was just great on the Highland roads.

Spend a little extra on the Adaptive M Suspension (£930) and you can adjust the ride quality as well.

Yes it is more of a grand tourer than a true sports car, but there’s nothing wrong with that.

The interior is well built and the extra space is much appreciated as is the improved visibility – up 14 per cent.

There’s a wonderful engine noise to be enjoyed – but only really when the aluminium roof is lowered.

Those straight six cylinder engines are great. But even when the roof is raised the cabin feels light and airy with a large glass area giving a feeling of spaciousness.

With the two-section roof lowered the wind deflector (well worth the extra £205) works superbly.

All three engines are petrol. The most powerful engine is the Z4 sDrive35i developing 306 bhp with two parallel turbochargers serving up 400Nm of torque and accelerating the car from 0 to 60 in 5.2 seconds.

It comes as standard with a six speed manual transmission but for it and the sDrive 30i there is the option of a six speed sport automatic.

The 2,497cc, 204bhp version with six speed manual or six speed auto transmission will reach 60 mph in 6.6 seconds, and hit 150 mph and average around 24mpg. This is likely to be the main seller,

There is also the 2,996cc engine pushing out 258 bhp again with a controlled top speed of 155mph and a 0-60 acceleration time of 5.8 seconds.

All three engines are claimed to average around 30 mpg – but if the car is driven as it should be, this figure will not be achieved. The two smaller engines push out 199 CO2 g/km and the 35i, 219 g/km.

Prices start as follows: Z4 sDrive 23i, £28,645, Z4 sDrive 30i, £32,660, and Z4 sDrive 35i, £37,060.

All version come very well equipped as standard with all the usual safety systems, air conditioning, but as with most German cars, there is a long list of quite expensive options available.

It is quite easy to spend an extra £10,000 on such items such as a navigation system, a pure white leather interior, and larger alloy wheels.

This really is a great improvement on the old model – yes the basic setting does give you a softer riding option, more akin to a coupe than a sports car, but a harder faster mode is just a button press away.

By Peter Carroll