THERE is a map on the wall of the office of GoinGreen's offices in Southall, West London, which shows the spread of emission-free motoring. It looks like the early stages of a virus, with coloured pins marking the address of every owner of a Reva G-Wiz.
So far, the map is restricted to Greater London. The armies of pins have outposts as far as Chislehurst and Beckenham in the south-east, and Wimbledon in the south-west, stretching as far north as Barnet. There are a couple in Ealing.
The big battalions are clustered in the leafier parts of north London, with high concentrations of colour in Primrose Hill and Hampstead. One of those pins is said to belong to Jonathan Ross - a man with a penchant for eccentric vehicles. Since they went on sale in summer 2004, more than 500 of these impish electric cars have been sold.
The analogy with a virus is apt. GoinGreen doesn't advertise its cars, instead selling them by word of mouth and through its website: www.goingreen.co.uk If the pins clump together, it's because the owners tend to recommend them to their friends. But the company did get a burst of publicity this week when the Conservative leader, David Cameron, posed with a G-Wiz (though the pistachio-tie-wearing politician actually drives a not very green Lexus GS 450).
It's to that same blue G-Wiz (reg: YK53 GOE) that I am led for my test-drive. The experience is made even more testing by the presence in the car of Graham, the photographer, and my guide, Joe Byars of GoinGreen. The G-Wiz is designed to seat two adults and two small children. It can take three tall men, but not without one of them doing an unseemly yoga position in the rear. And though the cabin is tall and the road position is quite high, the roof is no respecter of a gentleman's quiff.
The G-Wiz was conceived in California by Dr Lon Bell, an engineer who made his fortune making airbag sensors and seatbelt tensioners, before becoming intrigued by the way cars work.
In designing an electric car, he decided to ignore the assumptions of conventional construction. His first thought was to ask what was necessary in a car, from which he concluded that it needed wheels, with tyres, something to steer and a windscreen. Most of the rest was luxury and got in the way of making a nimble, no-frills electric vehicle for non-polluting urban travel.
As well as a body made from dent-resistant plastic, it has regenerative brakes: pressing the pedal works like a dynamo, recharging the engine.
It also has climate-controlled seating. Each seat has tiny heat-releasing holes which warm the body rather than the air in the car. There is a conventional heater, too, but using it will knock 10 miles from the car's 40-mile range.
Before we set off for the bright lights of Hayes, Joe flips open the bonnet to reveal a bottle containing windscreen fluid, and a small storage space. And that, more or less, is that. To the non-mechanically-minded, the G-Wiz is a remarkable piece of technology. It requires only a little more attention than a mobile phone, and it doesn't make an irritating noise in the cinema. To charge it, you stick a lead in the socket where the petrol cap should be, and you have to water the battery every two or three weeks. "It's like a plant," Joe says. "Every so often a light will come on saying 'Water me, please'."
This procedure is simpler then topping up a steam iron. You don't have to open the bonnet. You stick a small pipe into a hole by the plug, hold it in the air and pour in distilled water. You need never touch an oil can. Oiling is done during servicing. "You water your car," says Joe. "That's all you need to do."
Driving the thing is marginally more complicated, but will not test the aptitude of anyone who has ever sat in a dodgem. There are two pedals - an accelerator and a brake. The handbrake is a twisty device under the dashboard on the left of the steering wheel. The ignition is on the right.
This is the first big shock. When you turn on the engine, nothing happens. Actually, that's the point. There is no engine. When you turn the key you are not greeted by an angry growl of machinery. There is nothing, unless you count the flickering of a small green light on the dashboard. At first, this is disconcerting. Without the engine noise, the instincts of conventional driving don't kick in.
There is no pumping of the accelerator or gentle easing of the brake, and none of the sense of power which it is at the root of all car advertising. In this little moment of uncertainty, with no rush of testosterone to the places that make urban motoring slightly less relaxing than bare-knuckle boxing, it's tempting to forget the routines of driving - the mirror, signal, manoeuvre bit. Fortunately, such disorientation is not that dangerous. The G-Wiz seems to think before it moves, and when it does, it's a stately glide.
There are no gears. The car has a dial, with four modes: reverse, neutral, economy, and full power. In London, where the average speed of travel is less than 10mph, full power (with a top speed of 42mph) is rarely necessary, but it does offer slightly more oomph when easing from traffic lights.
On the open road, there is a perplexing absence of noise. Suddenly, you are aware of the volume from other cars' engines. Aurally, it's a bit like being a non-smoker in a cigar bar: you find yourself defined by the thing you are not doing. But it does make you wonder how much quieter our cities would be if all the short journeys were electric.
The car is cute in the way that Del Trotter's Reliant Robin was, and its green credentials are impeccable. But it is economically attractive, too. The G-Wiz is exempt from road tax, as it produces no carbon emissions. Since it costs only 40p to charge the car for 40 miles of driving, GoinGreen calculates that a London commuter will save the cost of the car (7,799 with free leather seats, worth 500) in a year.
The biggest problem for the spread of the technology is the need for off-street parking during the recharging process. Some London car parks offer recharging facilities, but flat-dwellers or owners without a driveway will need support from councils to make the G-Wiz a practical option.
Similarly, potential drivers outside London will have to wait until the company expands, or the technology becomes more universal, as servicing is currently only available at GoinGreen's headquarters. How does it feel? Well, not sexy exactly, but there is something endearing about the car that seems to bring out the best in other road users.
Thanks to the demands of the yogic photographer, Graham, I was forced to drive the G-Wiz in an irregular manner, circling the circumference of a roundabout 10 times, stopping in front of a bus, reversing in the wrong direction down a one-way street, and the reaction from other road users and pedestrians was one of tickled tolerance. Even White Van Man was smiling.
Lon Bell has compared the G-Wiz to the early mobile phones. In later models the batteries will be smaller and more efficient. A prototype of a hard-top roadster already exists: it goes at 80mph and has a range of 100 miles. That may bring more torque to the electric revolution, but it will be hard-pushed to replicate the Postman Pattish charm of the little G-Wiz.