Four audio sensors, small round discs, are placed along the front and rear bumpers.

When the driver wishes to park the car, he or she pushes the PDC button on the dashboard to activate the sensors.

As the car backs towards a rear wall, the sensors give out a beep - an audio warning of close proximity. The closer the car approaches, the closer the beep sounds.

In theory, it should be possible to park blindfolded.

Scientists tell us that bats and dolphins operate by echo location, whereby they emit a noise and listen for the echo - the reflection of sound waves from an obstructing surface.

The PDC system gives a BMW driver a chance of experiencing what it is like to manoeuvre by sound.

The intensity of the beeps gives the driver an accurate gauge of distance, which comes in handy parking in a dark garage or a dim driveway.

Even in daylight, the sensors can help preserve those precious bumpers and panels when backing up to low obstacles not visible in the rear-view mirror.

Because sensors have been placed along the corners of the bumpers, they also beep if the driver is pulling alongside a wall - for instance if he was driving up a typical Hongkong entrance way and had to pull over to make way for a car coming the oppositedirection.

And it takes the guesswork out of shuffling for space while crossing a place like the Tai Tam reservoir bridge and meeting a bus coming in the other direction.

On my test drive, I tried parking alongside a low concrete bench at Queen's Pier.

It was the sort of manoeuvre I would never usually attempt without getting out of the car several times and walking to the rear of the vehicle to check the distance.

The sensor gave out a loud insistent beep. Jumping out of the car, I went to the rear.

The bumper was about 50 centimetres from the bench, which was at the same height as the bumper.

Ordinarily, I would have felt satisfied with my parking distance, but I wanted to test my accuracy using this audio radar.

I released the brake and slowly edged the car backwards. The beeps quickened.

When they were a steady stutter, I stopped the car, went around to the back and measured the distance with a tape measure. The bumper was 10 cm from the bench.

This is perfect parking at the press of a button.

Because sensors have been placed along the corners of the bumpers, they can also act as audio guides along the side of the car.

The driveway to my flat - typical of many Hongkong apartment buildings - is a narrow uphill climb.

Going up one day, a taxi was coming down. I pulled over to the left, using the beeper to tell me how close I was approaching the retaining wall. For me, the audio radar system is the topping on a feast of attractive features.

The engineering, design and materials are so finely put together, that the BMW seems like the gentleman of luxury cars.

The generous cabin is decorated in understated elegance; the interior a well-appointed blend of leather and walnut trim.

The rear windows have pull-up sun shields, offering protection and privacy. They allowed me to pretend that I was too famous to travel unrecognised in public.

On the other hand, the attractions at the wheel are enough to make me give up the back seat, dismiss the chauffeur and drive myself.

With the perils of parking tamed by the PDC, driving a big car is a pleasure.