WE STILL may be a long way from witnessing the car that drives itself. But the new Mercedes-Benz S-class, which makes its world debut at this month's Paris Motor Show, is the nearest thing we've seen to it.

It is the most high-tech car ever launched, a wonder of high-tech electronics, all designed to make motoring easier or safer. And it is not the only electro-guided showcase for high-technology that is imminent. The upcoming Jaguar S-type, spiritual successor to the Inspector Morse MK2 and intended rival to the BMW 5-series, has controls that respond to voice commands. Dial a number on the mobile phone, turn on the radio, or set the cabin temperature, and you simply tell the car what you want, touching nothing. Your wish is its command.

Yet it is the pricier Mercedes that is more the Dan Dare car.

The satellite navigation takes into account current traffic congestion and advises a route.

Should the new S-class driver be unfortunate enough to crash - perhaps distracted by the voice synthesised navigation of the electronic co-pilot - the car automatically sends out an emergency phone call, pinpointing the exact site of the crash using satellite navigation.

Like the Jaguar, it also has a voice command system, which Mercedes calls Linguatronic. It enables the driver to dial a number on the mobile phone simply by saying the number. Equally, you can simply say a name, and as long as it's in the memory, the number is automatically dialled.

Even more futuristic is the radar-guided cruise control, an automatic co-pilot, in effect, that ensures a constant and safe distance between you and the car in front. It extends the function of the cruise control, by using a radar sensor in the radiator grille that scans the road ahead.

If the S-class gets too close to the car in front of you, the intelligent cruise-control unit automatically eases up the throttle and, if necessary, will even activate the brakes. After the distance widens, the cruise control system accelerates the car again. If you fancy living dangerously, you can always turn off the cruise control and start tailgating.

The new big Benz also has no key. The ignition and door key are replaced with a chip card which Mercedes calls `Keyless Go'. The chip card communicates automatically and electronically with the car. As long as the driver is carrying the correct card, the car recognises that the right driver is approaching. The card need not be waved in front of the door handle or ignition; it can be carried in a jacket pocket or wallet or purse. To unlock the car, you simply push one of the door buttons. To start the engine, all you have to do is simply push the starter button.

The new Jaguar S-type won't be quite as high-tech as the S-class Mercedes, not least because it will be substantially cheaper. But it will take voice- activated controls even further than the Mercedes. Bark orders like `Give me Radio Four unless it's Paul Gambaccini, ET phone home' or `20 degrees please' for your radio choice, phone number and air conditioning controls and the Jag does as it's told, like some sort of automotive genie.

The Jaguar's gizmos are the work of Ford's electronic subsidiary, Visteon. It is convinced that voice-activated controls are a technology of the future, and it's using the new S-type as Ford's upmarket guinea pig. Not that the systems haven't been thoroughly tested - unusually for a new Jaguar, they have been. But Ford would rather furrow new territory on a comparatively small volume upmarket car than rush straight in, and put it on the new Fiesta. Eventually, even the humble Fiesta will get it.

New electronic `breakthroughs' on Jaguars do not have good records, of course. The newfangled electrics on the 1986 Jaguar XJ40 led to a record amount of hard-shoulder motoring. I can imagine a few disgruntled owners shouting abuse at their cars, as the radio tunes into Chris Evans rather than Classic FM, or provides Arctic chill when the owner wants Saharan heat.

Mind you, I hope Mercedes' radar control works perfectly. If that fails, the results could be a bit more serious.