A lunch date in the city centre. Ordinarily I wouldn't think of driving. Not from where I live. You'd be mad to - the congestion, the charge for the congestion (because they actually charge you for that in London), the inevitable parking dilemma at the other end, the impossibility of timing your arrival within a window smaller than two and a half days... Madness. It's got to be public transport, every time.

Except this time. Because this time, out on my drive sits a Smart EV (for “electric vehicle”). You know about Smarts: urban micro-cars, built by Swatch in collaboration with Mercedes, only fractionally bigger than plimsolls, yet somehow offering transport for two people - though only ever for one of their briefcases.

Now Smart has bitten down even harder on the eco bullet and is trialling a plug-in electric one. A small number are available for business lease only. Commercial production may follow in a couple of years. And isn't this lunch appointment exactly what the Smart EV was born for - one of those short-ish dashes across town for which people would ordinarily use public transport?

So, away I go, and it's immediately apparent that this is potentially the biggest step we have seen so far in the electric car's evolutionary progress from milk float to something comfortable and not even slightly comical. True, it doesn't sound like a car. (It drones and whistles, a bit like a distant, taxiing aircraft.) And despite the manufacturer's assertion that it can run for 72 miles on a full charge, the prospect of it going flat somewhere distant from a plug is a real concern. (I decide to do without the radio and the heater to conserve energy.) But it has suspension like a car's. And it even accelerates like a car. Way forward!

Two miles into my journey, I realise that I am in a vehicle that is designed to combat global warming and I am freezing my nuts off. But that's just a local irony, above which one must rise and see the bigger picture. I am not smirching my city's air, nor in any measurable way making life tricky for polar bears. True, I am taking up more room and taxing the infrastructure of my city far more than I would have been if I had taken the bus. But I am taking up less room and taxing the infrastructure less than I would have been if I were in a Porsche Cayenne, which is a really ugly car in any case.

At Elephant & Castle, I cross into the congestion charge zone. But it is of no concern to me. I tip my head back and laugh in the face of those cameras. I am electric. I go free. Later, I will even park for nothing in a pay and display bay. I have read that I can do this but, because I don't quite believe it, I phone the council number on the ticket machine. And it's true. No need to buy permission to park at the gouging local rate of £3 per hour. Consider me incentivised. I am living the electric dream.

“What about bus lanes?” I find myself thinking. “Can I go in those?” And that speed camera over there, does that apply to me? I am, after all, in a far nobler form of transport and therefore, surely, above the petty concerns of the law as it affects others. Me and cyclists, both.

I complete the seven-mile journey in 40 minutes - breakneck speed for London - and achieve what is known in the business as “TV parking”, courtesy of a tiny slot right outside the place I need to go to. Did I mention that I was having lunch with the Princess Royal? Well, in the same building, anyway. Princess Anne did better than me with the parking. Her Bentley was backed up to the front door. But my Smart was not far behind, proximity-wise.

And then I buzzed home afterwards to plug the car into a wall socket. I like the idea that your car becomes something you leave to charge, along with your laptop, iPod, toothbrush, etc. On the other hand, I'm always forgetting to charge my mobile phone. Would I similarly forget to charge my car? Don't I already have enough things in my house that need charging?

Also, somewhat compromising the eco-advantages, the Smart EV would have to be a second car for me because, beyond delivering me roughly on time to lunch appointments with Princess Anne, it won't do anything I need it to do (principally, carry larger numbers of people and things over much longer distances).

Furthermore, won't I miss petrol stations? Miss the rituals, the community, the entirely unnecessary lateral purchasing of Starburst and Tic Tacs? Without petrol stations, where will I go for milk?

Top speed: limited to 60mph
Acceleration: 0-30 in 6.5 seconds
Range: 72 miles
Charging time: 8 hours (80 per cent charge in 4 hours)
Emissions: 0
Eco rating: 8/10
One careful owner: Bono
On the stereo: Human League
In the glovebox: no glovebox
Bound for: a plug socket
Marks out of 10: 7
Price: not yet available to buy