Renault Twizy: list prices do not include the Twizy's battery pack, which must be leased separately / Renault

No doors required. Renault reinvents the electric car

Price: from £6,690
Electric motor: 13kW/57Nm
Top speed (mph): 50 mph
0-28mph/45km/h (seconds): 6.1
Range (miles): 62
CO2 emissions: zero emissions at tailpipe but charged from UK electricity system (only 6.8 per cent renewables in 2010)

Renault is serious about electric vehicles. First there was the Fluence ZE, the plug-in saloon car for technophobes. That was followed by an electric version of the Kangoo van and soon there will be the Zoe, a battery-powered Clio-sized hatchback. But the one that's got everyone talking is the Twizy, on sale in the UK tomorrow.

So what exactly is the Twizy? That's a difficult question to answer. It has four wheels but it's not a car. It can carry two occupants, a driver and a passenger, but they travel in tandem rather than sitting side by side. It has a roof, like a car, but is open to the sides – unless you buy the optional doors and even they only cover the lower portion of the openings. It has a steering wheel rather than handlebars. It's a quadricycle, but with air- bags and disc-brakes, it's far more sophisticated than an average quad bike.

If it's hard to say what a Twizy is. It's easy to say what it can do and how it does it. It can substitute for a full-size car for just about any driver-only local journey, and probably most driver-plus-one-passenger trips as well – although your passenger will need to be fairly supple if he or she is to get in and out of the rear seat easily.

But it's the "how" bit that's really impressive. It may only have a top speed of about 50mph, but the Twizy has strong, smooth acceleration, so it has no problem keeping up with traffic. It's very manoeuverable, partly because it is so narrow, but you need to be prepared for the odd jolt if you hit a speed bump too quickly. Despite its small size and half-open body, you don't feel vulnerable when mixing it with larger vehicles; I think that's because you sit at about the same height as you would in a normal car. Above all, though, the Twizy is terrific fun.

Most electric cars have suffered in the market because of their limited range and steep pricing, but the Twizy chips away at these two problems. Its range of 60 miles is less than that of most other electric vehicles but the Twizy operates with a much larger margin of safety because it is likely to be used only for short urban journeys. Prices start at just £6,690, even though it doesn't qualify for the government's £5,000 plug-in vehicle subsidy. That's not much less than the cheapest "proper" cars such as the Kia Picanto but it may be low enough to tempt early adopters. They'll have to remember to budget at least £45 month to lease the battery, though, as it's not included in the list price.

The main reason for the Twizy's effectiveness seems to be its low weight – less than half of that of even the smallest conventional cars. Make a car lighter and you can make it go further with less energy. A light vehicle such the Twizy doesn't need power steering or a heavy brake servo, for example; that cuts weight further, allowing another round of savings to be made as other components can now be omitted or made lighter as well, and so on. Mass decompounding, the engineers call it.

This is where the real significance of the Twizy lies; by adopting a radically different architecture, Renault has started to transform the economics of electric vehicles. The Twizy is, in short, quite brilliant.

The competition

Manufacturers often claim that their new cars are innovative "category busters" with no direct competitors. Usually they're kidding themselves. In the case of the Twizy, it's true.

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