Andy RussellThe new Mazda3 2.0 Sport is mean, green and clean, says ANDY RUSSELL.When I first had a car I tried to save a few pence of petrol by turning off the engine in long queues of traffic.Andy Russell

The new Mazda3 2.0 Sport is mean, green and clean, says ANDY RUSSELL.

When I first had a car I tried to save a few pence of petrol by turning off the engine in long queues of traffic.

Some branded it the height of meanness but, in hindsight, it was an early example of greenness for automatic stop-start systems, which cut the engine in stationery traffic and fire it up again when the clutch pedal is pressed, are one way manufacturers are increasingly using to make their cars more environmentally-friendly.

Mazda has now introduced this technology on its new Mazda3 - calling it i-stop - but it's a shame it is currently available only on the 2.0-litre petrol Sport model.

Combine i-stop with weight-saving and improved aerodynamics and carbon dioxide emissions have been cut by 19pc from 189 to 159g/km - dropping it six company car tax bands - while combined fuel economy is 16pc better, up from 35.8 to 41.5mpg. Although I averaged only 34mpg, my test car arrived with barely 600 miles on the clock so the engine was still tight and fuel economy will improve.

All very well on paper but how does it work in practice?

It's all very clever. The engine stores the combusted fuel mix to restart quickly with only a little help from the starter motor and without using too much fuel. Once warmed up, when the engine stops, the pistons, crankshaft, valve opening and direct petrol injection are precisely tuned with one another so i-stop effectively 'pauses' the engine, rather than stopping it. It means it's poised on 'stand-by' to start again in 0.35 seconds - twice as fast as conventional start-stop systems.

But won't all that restarting put a strain on the battery, I hear you ask.

Not at all - it has two batteries. The main one provides the general energy supply, so lights, audio system and all other electric systems still work - even the climate control provided it is not running full blast - with the engine off while a sub battery is exclusively for starting the engine.

Despite its green credentials the 2.0-litre engine is flexible at low revs and decidedly peppy on the move when you make use of the slick-shifting six-speed gearbox and the sports exhaust has a lovely rasp.

The new Mazda3 is much more stylish than its predecessor, especially with the Sport model's side skirts, rear spoiler, sports bumpers and 17in alloy wheels filling out the wheelarches. It also turns up the heat on the big three of the Ford Focus, Vauxhall Astra and Volkswagen Golf with driving qualities that are far more dynamic.

It's a brand that in the past has been lauded for being reliable and worthy but, in the main, not the most exciting of drives - disappointing given the fun factor of the evergreen MX-5 sports car.

That has all changed with the new range which follows the lead set by the bigger Mazda6.

The low-speed ride is quite firm, but not unpleasant, but gets smoother at speed although there is noticeable tyre noise. On the upside, it really sticks to the road with first-rate body control, a taut and agile feel through corners and well-weighted steering.

Inside, even though legroom does not look generous, it will seat six-foot passengers front and back. The well-shaped boot offers decent load-carrying capability and you appreciate the low sill when lifting heavy items in and out. Rear seats split 60/40 and fold flat.

What I really like about the new Mazda6 and Mazda3 is the stylish new fascia with big dials and sensible knobs and buttons, which are easy to find and use. The i-stop model gets keyless entry and ignition - there's a button to fire it up and stop it - and I was always impressed by the way the dashboard came alive with the speedo and rev counter lighting up, followed by the blue lighting on the radio/CD and finally the temperature controls.

Good all-round adjustment for the steering wheel and well-bolstered sports seat create a comfortable driving position. While the cabin is well designed when it comes to ergonomics and storage space and boasts a good fit and finish, I thought the Sport model felt rather sombre with a lot of dark grey and black plastic trim and fabric with not a lot to break it up apart from some metallic-effect panels on the dashboard and centre console.

At �18,025 the 2.0 Sport is good value too with a generous array of safety equipment and creature comforts including anti-lock brakes, stability and traction control, front, front side and curtain airbags, rear parking sensors, automatic headlamps and wipers, front fog lights, dual-zone climate control, remote deadlocking, cruise control, satellite navigation, heated windscreen and front seats, 10-speaker Bose sound system, six-CD autochanger and Bluetooth phone link.

The Mazda range, like its sales, goes from strength to strength with the Mazda3 now serious competition against big-selling rivals rather than an also-ran.

MAZDA3 2.0 SPORT i-STOP

PRICE: �18,025

ENGINE: 1,999cc, 151PS, four-cylinder petrol with automatic stop-start

PERFORMANCE: 0-62mph 10.4 seconds; top speed 128mph

MPG: Urban 30.4; extra urban 52.3; combined 41.5

EMISSIONS: 159g/km

BENEFIT-IN-KIND TAX RATE: 19pc

INSURANCE GROUP: 9E

WARRANTY: Three years/60,000 miles

WILL IT FIT IN THE GARAGE: Length 4,490mm; width (excluding door mirrors) 1,755mm; height 1,470mm