BOLTING big wheels on a car is a bit like the way some approach high heels - they look good but you know they'll hurt.

Not, in the case of a car, with shootings pains in the ankle, but in the owner's wallet.

They're going to cost more in the first place, but there are less obvious downsides.

Your smart set of big alloys will make the car burn more petrol and produce more pollution - and probably stiffen the ride on rotten roads too.

All of which - especially if you regularly head into London - means you ought to be careful to choose the right version of Toyota's Yaris Hybrid. The wrong one will cost.

This most economical of Yaris models - all of which had a seriously thorough mid-life makeover a year ago - comes with a combination of petrol engine and electric motor to give deeply impressive on-paper economy figures.

In real life you won't approach the official figure (nearly 80mpg in this case) but a dashboard readout the right side of 58mpg after 500 miles of mixed driving was far from shabby.

Thing is though, this car was a posh Excel version, whose added bells and whistles includes bigger alloy wheels (16in instead of the 15in fitted to the Icon model) and they hit the fuel consumption figures.

Bigger wheels mean wider tyres, which take more power to turn. You lose economy (down from 85.6mpg to 78.5mpg in the official test) and, more important perhaps, the tailpipe emissions rise above the London congestion charge threshold.

The jump from 75g/km to 82g/km of CO2 makes the car liable for the £11.50 daily charge if you venture into central London. Choosing Excel over the Icon grade of Yaris also pops another £1,500 on the bottom line.

Then you discover that Toyota has grasped the irony of paying more to pay still more and will deliver your smarter grade Yaris Hybrid with the smaller wheels - thus saving you money if you're a regular capital visitor. Sadly, there's no mention of charging a little less for the car on its cheaper alloys.

But enough of economy; whichever of the two versions you choose will quickly impress in other areas too. Notably in the way the car drives; in near silence for short stretches at low speed with just the distant whine of an electric motor (like a Tube train as one passenger put it).

It must be about the easiest car to drive you'll find this side of a prototype that steers and stops itself. The Yaris won't do that, but its automatic gearbox and light steering combine to make it a delight in breath-in-tight town work.

Add in seats that set you comfortably upright, and tight exterior dimensions, and the Yaris - for all the added street presence styling added at its makeover - is just right for making unobtrusive progress in crowded streets.

Out in the country, or indeed on motorways, it holds it head high with a decently hushed interior combining with enough space for four and a ride that stays controlled under the provocation of a typically British road surface.

I think the practicality of this car shows best in the cheaper Icon model but you may be tempted by the DAB radio, cruise control, automatic lights and wipers, part leather seats and LED running lights that the £1,500 jump to Excel trim brings.