Softly, softly. You'll never hear them coming

Hampshire Constabulary believes its new electric patroller, a Ford Ecostar, will have operational benefits over conventional diesels. Such as stealth. The chance of approaching villains silently at night has not been lost on the beat bobbies. Another advantage is that this hi-tech experimental electric will sprint to 30mph from standstill - which is quicker than a comparable petrol car.

The vehicle to be evaluated by the Fleet station around Farnborough, Alton and Aldershot over the next 30 months is one of 103 Ecostars - all based on the shell of an Escort van - that Ford has built for real-life trials. You cannot yet buy one. Nor would you want to at today's prices. The vehicle on loan to the Hants police is being sponsored by National Power.For it is the electricity generating companies that stand to gain most from the coming electric car revolution. And come it will, as surely as the world's finite reserves of fossil fuel will expire.

Technically, the Ecostar is as far ahead of Sinclair's grim C5 as Concorde is from a Tiger Moth. In busy London traffic, it was even easier to drive than the petrol automatic the American-based design team sought to emulate. Learners bamboozled by clutch and gear lever would find it a doddle. To activate the powerful computers and complex electronics, you turn a conventional "ignition" key. A green light comes on to indicate all's well. When drive is selected, with a conventional floor-mounted lever with P R N D markings, the Ecostar tends to creep from rest like an automatic. There are no gears to change, either. The 75 horsepower AC motor, which runs at up to twice the speed of a normal petrol engine (to a dizzy 13,500 revs per minute), drives the front wheels through a one-speed gearbox.

Unlike a petrol or diesel engine, an electric motor develops massive pulling power at rest, so Ecostar accelerates from standstill with unexpected vigour and uncannily little noise. As speed increases, zap subsides, but acceleration within urban limits is never less than sprightly. The drive-by-wire accelerator pedal feels like that of a petrol-powered car. It was a priority that all Ecostar's controls should have familiar feel.

Back off and the car slows discernibly as motor becomes generator, feeding electricity back to the batteries as the regenerative braking system snaps into action. The Achilles heel of electric vehicles running on conventional lead-acid batteries is that they fizzle to a halt, energy exhausted, after 30 miles or so. Ford has addressed the problem on Ecostar by using state- of-the-art sodium-sulphur batteries that give three times the mileage of ordinary ones of comparable weight. Ford reckons it's got as many as l54 miles from one Ecostar, but concedes that the average is around 100 miles - much less than normal but adequate for an urban runabout.

No electric vehicle is capable of sustaining motorway speeds for 300- 400 miles, even less one that can be recharged in the time it takes to replenish a normal fuel tank. There's no short cut to the five-seven hours needed to recharge the Ecostar's battery - at any domestic socket provided you have the right adapter. A full charge, say six hours at 30 amps, costs about £l.20, says Ford, so running costs are competitive.

The big snag with Ecostar's dedicated prototype batteries is that they cost more than £30,000 apiece - though the price would tumble with volume production, perhaps to as little as £1,000. By the turn of the century, Ford believes that a viable electric car might carry a 10 per cent price premium, the extra spent on batteries being offset by savings on the motor, which is cheaper than a conventional engine.

Weight remains a problem. Ecostar's multi-cell battery, slung low beneath the cargo floor so the vehicle's handling and balance is not upset, weighs around 350kg, 6.9cwt. Although weight savings have been made on the van itself, Ecostar is still 25 per cent heavier than an ordinary Escort. Even so, it felt stable in city traffic, and steered easily without power assistance.

Ford dismisses fears about safety. It reckons a tankful of petrol is no less hazardous than a third-of-a-ton of battery operating at 300 C - three times the temperature of boiling water. Ideal for delivering pizzas, perhaps, but not ice cream. For protection and insulation, the battery cells are contained in a sand-filled matrix encased, like a vacuum flask, in glassfibre and double-skinned stainless steel. Ecostars have survived test crashes without calamity, says Ford. Extra heating is provided on cold-climate cars by a diesel-fuelled burner, which supplements the battery- powered heater/air conditioning.

Problems with range, performance and recharging will restrict electrics such as Ecostar to being urban runabouts unless there's a breakthrough in battery technology. Meanwhile, California, with its stringent emissions regulations, is becoming champion of the electric car. In 1998 the polluted state will demand that 2 per cent of all vehicles sold - about 25,000 - should have zero emissions. That means 25,000 expensive electrics with low-tech batteries (nothing else is commercially viable), poor performance and pathetic ranges. Who will buy them? "The industry is not ready for mandated sales of electric cars," commented Ray Day of Ford.

Ecostar has cost Ford $150m so far. Now the company has joined forces with GM, Chrysler and the US government to seek that Holy Grail: the long- range, high-performance battery.