IF diesel is a dirty word in some corners of the car world, perhaps the immediate future lies with petrol power.

At least until we're all plugging our cars in at night or looking for a fill of high pressure hydrogen.

So, if petrol persists, what's the best way to make a gallon go as far as possible, softening the hit to our wallets and pumping out fewer nasties at the same time?

The obvious answer is to make the engine smaller. Or so you might think, until you drive one of the new runabouts with a tiny powerplant.

They flatter to deceive in the official economy tests and you'd need to drive them as though the accelerator pedal was white hot to get within miles of the quoted figures.

Another approach to economy - and a brave one in a world where people think smaller is better - is to put a bigger engine under the bonnet and give it an easier time.

Which is what Mazda has done with its pert looking Mazda2 hatchback, now available as a high value special edition called Sport Black, confusingly available only in metallic white or dramatic red and costing £15,395.

It's the add-on body styling kit that comes in black, adding a touch of dark menace with front and side air dams and a rear roof spoiler.

Alloy wheels in smart gunmetal finish, front fog lights, auto headlights and wipers, rear parking sensors, rear privacy glass and chromed exhaust trim complete the visual upgrade.

The Sport Black is based on the 1.5 litre, 89bhp Mazda2 SE-L Nav model and costs precisely £1,000 more. That looks decent value considering the metallic paint alone is worth £650.

You can make your special edition stand our further with graphics on the side of the car but I'd save the £336.64 they cost and enjoy the unadorned shape of one today's better looking small hatches.

Either way, you would end up with a car that is entertaining to drive, thanks to a willing engine (114mph, 0-62mph 9.4 seconds) and enough verve in the suspension, steering and gearchange to let you look forward to the twisty bits. A firmish set of springs seems a small price to pay.

So back to the engine, at 1.5 litres a lot larger than rivals where a mere 1.0 litres (and three cylinders to the Mazda's four) is increasingly the norm. Well, after a brisk drive on everything from country lanes to the M40 at a 'businessman's pace' the car showed 52mpg on its easily read dashboard.

That is some way from the unrealistic 63mpg Mazda has to quote for the official test but miles nearer that figure than any of the smaller engined rivals I have tried. Its 105g/km CO2 output means free road tax in year one and a mere £20 thereafter.

You might find the resolute blackness of the Mazda2's interior a bit sombre; it's a characteristic of most modern Mazdas and I think gives them all a sense of serious purpose.

No doubting the quality of the fit and finish of everything from switches to door handles and every survey shows that Mazdas outlast most of the opposition and go wrong rarely.

The standard fit sat nav is worked from a control knob between the front seats, which is extremely convenient and must cost Mazda more than sticking everything on a distant touch screen.

Typical, really, of this company's approach to car design where more can still be better sometimes.