Toyota iQ

The iQ does one thing brilliantly. Parking. Which is OK, because for the urban driver, parking is the main headache. It does several other things perfectly competently too. It's easy to drive in traffic, it's nicely designed. Most of all it sends out a signal that you, y'know, care about emissions and traffic and all that other car-type badness.

So the minimal-emissions engine option, the little 1.0 three-cylinder, is conceptually right for it. Unfortunately even the most dedicated fan would have to concede it ain't up to the job of propelling the iQ along a motorway, not when the gradient goes against you, or if you need to get smartly into the outside lane when a gap appears. This new 1.3-litre four-cylinder is better at that: it will provide actual acceleration above 60mph.

It's not as charismatic an engine as the three-cylinder. It just mumbles tediously away. But iQ buyers aren't looking for mechanical charisma. Neither are they looking for a fun way of negotiating backroads or roundabouts, which is just as well, because while the 1.3-litre can provide the power for that, the suspension's roll and pitch and understeer and general wobble makes the experience all too queasy. That's inevitable when the wheelbase is so short and you sit so high.

But on the bright side, the emissions from the 1.3 are still pretty commendable, at 113g/km for the manual, aided by a quick-witted and smooth new stop-start system to kill the engine at red lights. Or you can have a CVT. I think many buyers will, given that they're not the sort of people who like the act of driving. It's smooth if you're gentle, but makes the usual outboard-motor hysteria if you try to wring its neck. Emissions with the CVT though are 120g/km, and that option takes it to £12,500.

Which is a lot for a car with such a cheaply made cabin - scratchy plastics, switchgear like a market-stall DVD player. The iQ chief engineer admitted to me he'd made an error not forcing a better cabin past the management, and he says nicer trim pieces are in design already.

Even after all that, I still want to love the iQ. I live in a city and I love cheeky parkable cars. And I'm bowled over by the engineering effort and ingenuity that has gone into making it so tiny and safe. But as an only car it's untenable.

Paul Horrell