Blue is green; a matter of OPINION in association with fish4.

Byline: By Alistair Coull and Val Jessop

GREEN is what we are all trying to be in the battle to cut our carbon footprint. For Volkswagen, however, green means blue - as their range of Blue Motion models reaches new heights of economy motoring.

For the VW Polo, that means over 74 miles to the gallon thanks to better aerodynamics and a bespoke turbo diesel engine.

A week with a Polo Blue Motion proved to me why it is so popular - it has absolutely everything you want from a super mini - comfort, fuel sipping economy and an absolute gem of an engine even if it can and does sound like a rattly tin of nails when you start it up and at low speed.

The three-cylinder 1.4-litre turbo diesel power-plant is reasonably quick - a top speed of 109mph and acceleration from a standstill to 62mph in 12.8 seconds.

But it is its superb economy that really impresses.

No matter how hard I tried I couldn't match the official 74mpg figure. The best I could manage to average was the high 60s - probably because I do a lot of motorway driving - but I think that's still a remarkable result for a large super mini that can seat four adults in complete comfort.

Blue Motion is a success and the 144lb/ft of torque from only 1800rpm really makes driving a pleasure once you've mastered the need to make frequent gear changes.

The slightly noisy engine is a small price to pay for the fuel economy returns.

The Polo Blue Motion is available in both three and five-door body styles and with two trim levels.

All share the same 1.4-litre 80PS 144lb/ft three-cylinder engine which has Electronic Gas Recirculation and a diesel particulate filter.

A revised five-speed manual gearbox has 'longer' third, fourth and fifth gear ratios to maximise fuel economy and lower carbon emissions.

But what makes them so eco-friendly?

The aerodynamics have been tweaked to smooth airflow over the car with a new grille, an extended lower lip on the front bumper, an integrated wing to the trailing edge of the rear window and the use of low rolling resistance tyres fitted to lightweight alloy wheels.

All Blue Motion Polos have antilock brakes, front and side airbags, power steering, electric windows, electrically heated adjustable door mirrors, trip computer, radio/MP3 compatible CD player, five headrests and Isofix child seat fixings.

In Blue Motion 2 guise, there is climate control, automatic come home lighting, rain sensing wipers, leather trim for steering wheel, gear knob and handbrake, and remote central locking.

YOU cannot fail to be impressed by Volkswagen's commitment in trying to reduce the carbon footprint.

The Blue Motion treatment to certain models, including the 1.4 diesel test car, is to be commended, but others may think that tweaking gear ratios, along with other firklings, detracts from creature comforts - such as a cabin insulated from overly harsh engine noise. I agree.

The greening process, or rather the Blue Motion treatment, has resulted in reducing pollution of one kind, in exchange for another: that of noise. What a pity.

The oil-burner's three-cylinder unit is competent and frugal, but what a rowdy operator, especially in low gears, emitting a clattering overture several decibels above tolerance level. It needs sorting.

The actual Blue Motion treatment involves making the upper ratios longer, with third, fourth and fifth gears extended to reduce engine speeds and maximise economy.

In fifth gear, 70mph equates to a little over 2,000 rpm.

There is a new turbocharger to improve performance, low-resistance tyres and a diesel particulate filter.

You have to change gear a lot more to keep up the momentum, especially on hills, which tends to nibble into the impressive fuel return figures.

Nevertheless, the 1.4 Polo steers and handles well.

The Polo Blue Motion avoids the London congestion charge and its CO2 rating of 99g/km, also exempts it from vehicle excise duty.

It returns over 57mpg in town, an incredible 88mpg at a steady 56mph with an average of 74mpg.

The five-door car on test - in Blue Motion 2 trim - costs pounds 13,565 and it's likely to prove the favourite with buyers.

Prices for the Blue Motion Polos are up to pounds 1,000 more than the comparable-engined SE models, so that's quite a hike, but it's easy to appreciate these differentials could be clawed back on the superb fuel economy alone, but it would take some time.

However, cars like this are supposed to help us focus more on reducing pollution and encourage us to be more responsible and caring towards the environment. So if you plump for a Blue Motion you can at least give yourself a pat on the pack with the knowledge that, little by little, you're helping to save the planet.

VW Polo 1.4 TDI BlueMotion

ENGINE: 1,422cc 3-cyl 80PS@4,000rpm 144lb/ft@1,800rpm

PERFORMANCE: Top speed: 109mph 0-62mph: 12.8 secs

ECONOMY: Town: 57.6/open road: 88.3/mixed: 74.3mpg CO2 EMISSIONS: 99g/km

INSURANCE: Group 5 PRICE: pounds 13,565