NOISE is sexy. In the world of the fast car, the greater the racket as the engine shakes windows four streets away, sets off alarms and generally irritates elderly folk with hearing aids, the more potent its performance is sure to be. Watch any four-year-old lad playing with his toy cars. While the car is held in a little fist, scratching gravity-defying turns on the newly painted walls and the polished antique table, the child all the while emits a song of “vrrrroom-vrooms”, roars and wails.

Which is why BMW has decided to make its newest sportscar noisier. In an automotive world in which designers and engineers spend hundreds of man-years giving car interiors the deathly hush of a funeral parlour, the goal with the Z4 has been the opposite, with BMW experts trying to pump as much engine noise into the two-seat cabin as possible.

Duncan Forrester, of BMW, said: “We set out with the Z4 to bring the engine noise back into the cabin. With a car like this, it is essential that the driver can hear the engine, what it is doing, and what is going on under the bonnet.”

BMW boasts of having 100 “acoustic engineers” on its books. Their work means that the BMW 7 Series saloon whispers along in a vacuum, the driver worried about having gone deaf. At traffic lights, only a furtive glance at the rev counter tells you that the engine hasn’t died. By contrast, the Z4 is motor-din heaven. Like a decent audio system, the car’s engine sound management system has been tuned to get the most out of the motor. Noise from the engine is fed into the cabin, with intake system pressure noises from the intake manifold, instead of being killed off with yards of felt matting. It arrives in the cabin via a tube and a flexing diaphragm. The result is a high-octane backing track.

Sitting at the wheel of the 3.0 litre Z4, blipping the throttle, is to be that 4-year old car-mad tot once again. The noise is terrific. Not deafening, or violent, but very, very purposeful. Well worth the effort of all those engineers. The car looks as good as it sounds, too.

At a café between Aberdeen and Balmoral, I stopped and chatted with three leather-clad bikers, having a cigarette break next to their gleaming Harley-Davidson motorcycles. Bikers are harsh car critics at the best of times, but they were intrigued by the Z4, and agreed that its looks, with its slashed edges and stumpy tail, are much more the business than the more lightweight, “girlie” Z3 that the Z4 succeeds. Almost half of all Z3s were bought by women but BMW expects around 70 per cent of Z4 buyers will be men.

The Z4 engine develops 231 bhp, covers 0-60 mph in six seconds and has a top speed of 155 mph. Which is enough. There is also a six-speed gearbox, and a clever button to push that gives the car sportier handling and more responsive acceleration.

But what makes the Z4 work is the seating position. You sit very, very low down, the elongated bonnet tapering away in front of you. Your backside over the back-axle, you really do drive by the “seat of your pants”.

It can be a harsh ride with the sport suspension, as you travel rapidly over twisting countryside roads. The Z4 suspension is unforgiving, and the car’s body is absolutely rigid, much stiffer than the Z3. The result is a car that has excellent response and brings real confidence through corners.

The brakes are superb, anti-lock coming in without fuss when needed, though in Scotland to stop in summer is to risk the midges, which is where the Z4’s fabulous roof comes in. Whether travelling from up to down or the other way, the Z4 roof makes the trip in around ten seconds, fast enough to beat the rain. It is all-electric and self-fastening.

There is also a 2.5 litre version of the Z4 which, at £26,655 is conderably cheaper than the 3.0 litre. However, the bigger engine is the one to go for. The 2.5 litre engine has to be driven at high revs in most gears to feel any snap, crackle and pop. Even then, it does not respond as instantly, or sound anywhere near as alluring as the 3.0 litre model. The Z3 had its critics as a driver’s car, though few could deny it was pretty, easy to own and great fun in the sun. The Z4 shows a different face. Its looks will also attract critics, but few will be able to disown its performance, handling or vroom-ability. BMW knows that the Z4 has a fight on its hands. This is a market in which high-quality cars abound. The two most obvious rivals are the Porsche Boxster and the Audi TT Roadster. The Z4 should prove itself more than a match.

BMW Z4 facts and figure

Price: £30,855 on the road
Engine: 3-litre in straight six-cylinder configuration, producing 231bhp at 5,900rpm and 221lb ft of torque at 3,500rpm Performance: Top speed 155mph, 0-60mph in six seconds
Economy: 20.9mpg in town, 42.8mpg on motorways
Equipment: Includes air-conditioning, run-flat tyre indicator, front and side airbags, sports suspension, leather upholstery, 17-inch alloy wheels
Rating: Entertainingly noisy