Imagine someone is trying to steal your car. As his hand pulls on the door handle, he ignites a bottle of gas hidden in the car’s sill. Two seconds later and his car-stealing days — and any other kind of day for that matter — are over as he is torched by a ferocious flame. If this gadget sounds as if it’s been dreamt up by James Bond’s Q, think again. It’s real, it’s available and all you have to do is live in South Africa and know where to find it.

Over here, the police have a less relaxed attitude to anyone implementing such innovative self-help measures, despite a recent rise in car crime.

According to the latest Home Office figures, car crime rose last year for the first time in a decade. Police in England and Wales recorded 328,000 vehicle thefts and 655,000 thefts from vehicles. Overall there were 15,000 more offences than the previous year — throwing off course the government's goal of reducing car crime by 25% between 1999 and 2004.

One problem with reducing offences is that the nature of car crime is evolving. Experts believe numbers of offences have been falling in recent years as car security systems have improved but the rise in 2002 suggests the thieves may have managed to catch up with the technology, or switched tactics.

Car alarms are no longer seen as effective because their tendency to go off accidentally means that they are often ignored. The big setback for the thieves came in 1998 when it became mandatory for all new cars sold in Britain to be fitted with immobilisers. The thieves switched to nicking older cars instead.

But these easy targets are becoming scarce, so the thieves have turned their efforts to beating the immobilisers. The cars most at risk are not top-end Ferraris and Bentleys but more mainstream quality machines such as BMWs, Audis and Mercedes. Own one of these and you can bet that someone has already hired one, taken it to a workshop, dismantled it and tried to find a way of outwitting its security systems. And these guys are very, very clever.

Even if they draw a blank, there’s still an easy alternative: these days the holy grail for any would-be thief is no longer your car but its keys. Steal those and the best standard-fit immobiliser will be powerless. And now that houses are easier to break into than cars, if you leave your car keys in view on the mantelpiece or within easy reach in the hall you might as well have left them in the ignition.

But the biggest growth area in vehicle crime is carjacking, with one report suggesting 1,200 incidents in London alone during 2001. The attraction is clear: in one swift action you get the car, its keys and away, usually in less than 30 seconds. Some police forces are so concerned that they have established special squads to deal with it. And no wonder — historically one of the few positive things that could be said about car crime was that rarely was anyone hurt. With the advent of carjacking, people are dying, most famously the south London estate agent Timothy Robinson, who was knifed last year in a suspected carjacking. Other countries’ experiences show that it is a crime that can quickly reach epidemic proportions: in South Africa there are 12,000 carjackings every year.

Luckily, new technology is here to help. For some years it has been possible to fit vehicle locators, such as the Tracker system, and these have proved highly effective, recovering more than 90% of stolen cars. Now the technology is taking the next step towards stopping the thief getting away at all.

A company called I-mob Interactive Vehicle Security has launched a system that allows you or the police to immobilise the car with a telephone call. When the car is stolen you automatically receive an alert call and can authorise immobilisation. If you are carjacked, you need only reach for a telephone as the car disappears round the corner to stop it.

In fact the car won’t stop immediately because, depending on its location, that could be dangerous. Execution is delayed until the next time the car comes to a natural halt, such as at traffic lights, when it will immobilise itself and turn on the hazard lights. A GPS (global positioning system) tracking system then lets you know exactly where it is.

One neat optional feature of I-mob is the ability to talk to those inside the car, so if you want, you can have the pleasure of informing your assailant that the car will shortly immobilise itself, and that the police are on their way. This has the advantage of scaring the thief so that they will be unlikely to waste time vandalising the car — they will probably make their escape on foot immediately.

However, if you would rather see justice done you could keep quiet and allow police to track the car, corner the thief and make an arrest.

The system will also contact a call centre in the event of an accident, allowing two-way conversation between the occupants and I-mob staff to establish if the driver is injured and to call emergency services. The system is available, fitted, from £970.

BlackJax is another anti-hijack system, sold by the renowned specialist Clifford. It detects a door opening and closing and a driver getting in and out. Before the car is driven away it asks for a code to be input into a key pad. After the third failed attempt the car is immobilised, the lights start to flash and the siren sounds. It costs about £165 and can be incorporated into other Clifford security systems.

Autowatch sells a similar system which immobilises the car if you do not flick a concealed switch as you move off after starting the vehicle. Like I-mob, the system even works if somebody has stolen your car keys.

Other novel systems are available: Toad offers a facility to make your car fill with a dense white smoke should anyone attempt to steal it, making it impossible to drive. And there are a variety of audible warnings should someone get too close. People have been known to “sample” Arnold Schwarznegger doing his best Terminator impression and blast that out of the car in order to turn the thieves away.

But one of the most appealing to many victims is the Autotaser. To the uneducated eye, the Autotaser looks like a simple bar-type steering lock. However, should it detect motion inside the car it sets off an alarm loud enough to put off most thieves. Should this not work, and the thief is persistent enough to try to remove the Autotaser, he will receive a 5,900 milliwatt electron pulse through his fingers.

We are assured this is a non-lethal dose but also that the thief is unlikely ever to forget the experience. Sadly, but probably sensibly, the Autotaser, native to Texas, has just been withdrawn from the market.

I-mob Interactive Vehicle Security System www.alansmith.co.uk/alarmselect/tracker1.htm
01494 512 922

Autowatch 68Hi Anti-hijack unit, £199 inc installation
www.autowatch.co.uk
0845 602 4276

BlackJax Security code to prevent immobilisation
www.clifford.co.uk

Toad anti-carjack systems
www.directcarparts.co.uk/toadalarms.htm
0191 516 6426