This car is far from the finished article, but it demonstrates how the vehicle which represents a sea change in how we think about eco-cars, will work in practice.

This stickered-up Cruze is a priceless development car incorporating the technology which will eventually find its way into the Vauxhall Ampera - a sexy four-door which promises to be the most viable eco-car yet.

Climb inside, and the Ampera doesn't feel futuristic. There are no Starship Enterprise-style lights, buttons or levers; just a push-button start, an automatic gearbox and a couple of pedals, like a conventional auto.

Fire the system up and it hums into life. Release the brake and the car moves forward silently. It goes, stops and turns like a normal car, which is what Vauxhall wants. It says buyers want mobility, space and affordability as with a conventional car.

Vauxhall says it'll reach 62mph in nine seconds thanks to 272lb/ft of pulling power. Overtaking grunt is equally impressive, thanks to all that torque being instantly available; top speed is 100mph.

The bizarre thing is it does everything with but a whisper, leaving only a whiff of road and wind noise to break the silence. It's an eerie experience for motorists used to a throbbing engine note, but one we'll be getting used to soon.

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Under the bonnet sits a petrol engine, a generator and a motor, plus a battery pack - but this isn't a hybrid, it's an E-REV - Extended-Range Electric Vehicle.

A hybrid's electric drive system is merely assistance for a petrol engine; an E-REV is always powered by the electric motor. When the battery is nearly flat, a 1.4-litre petrol engine kicks into life to top up the battery to make it good for another 300 miles.

Vauxhall is expecting the Ampera to emit an official average of 40g/km of CO2. According to its calculations, a daily commute of under 30 miles will cost 80p.

The bad news is that the Ampera will almost certainly be more expensive than the similarly-sized Astra, and it's unlikely owners will be able to get their Ampera serviced at many of Vauxhall's dealerships at launch.

But Vauxhall is pushing the government hard on making the Ampera an appealing proposition for buyers. The company wants the Treasury to offer tax incentives and utility companies to provide cheaper, off-peak tariffs, and planners to ensure all new garages have 240-volt outlets.

All of these will undoubtedly help buyers into Amperas, but the car's ability and clever design means it deserves to be at least as popular as the Toyota Prius. I've seen the future, and it has a Vauxhall badge.