THE CX7 has, until now, been one of Mazda's less successful cars on the UK market.

It wasn't hard to see why. Despite the chunky body, four-wheel drive, oodles of high tech kit and keen pricing the CX7 was saddled with a gas guzzling 2.3-litre petrol engine as used by the 3 MPS.

Mazda hoped to convince buyers that the CX7 was different - an SUV with performance to match a hot hatchback - but the market was unimpressed.

Two years after it first went on sale, the CX7 finally gets the diesel engine it so desperately needs.

And to mark the change it receives a mid-life refresh. Externally the chin spoiler is lower, the fog lights are new, the rear bumper has been re-profiled and there's a larger roof spoiler.

Chunky 19-inch alloy wheels are now standard and the boot handle is trimmed with chrome plastic.

The distinctive bulging wheel arches (a Mazda trademark), hints of the sporty RX8 about the nose and the kinked shoulders remain as before.

That's no bad thing (the CX7 was always a good-looker) and, because so few have been sold to date, it's unlikely you'll see any others on the road for awhile. So the neighbours will still know you've got a new SUV.

Inside the cabin it's a bit like a parts-bin special: the steering wheel is familiar if you've ever sat in an MX5 and the instruments are reminiscent of the RX8. That's fine when the parts are from decent donor cars.

The build quality is good (although the boot lid's interior grab handle fell out during the freezing cold weather) and I'd have confidence in the CX7's longevity.

There's plenty of room for five adults in the cabin - the CX7 is larger than several SUV rivals - and during a Christmas holiday expedition to enjoy the snow the big boot was well up to the job of swallowing our sledge, several pairs of wellies, blankets (because you never know) and a big bag packed with hot soup and chocolate bars. There's no third row of seats waiting to pop up from the luggage area, though, the CX7 is strictly for five.

The new 2.2-litre turbodiesel is a refinement of the similar engine fitted beneath the Mazda 6's shapely bonnet.

An uprated turbocharger and more efficient inter-cooler help boost torque for better pulling power - exactly what's needed for a big, butch 4x4 that weighs a not inconsiderable 1,800kg.

Acceleration is lively off the mark and on-gear flexibility is good. During the recent snowy weather the CX7 would trickle along at walking pace in third gear as I crept across roads turned to ice, then pick up smartly when I came across a surface that had been gritted.

The big wide wheels and low profile tyres did compromise outright grip in the snow, however, and once or twice I had cause to be thankful for the anti-lock brakes. Maybe that's why Mazda suggests the Mazda isn't really a full-on off-roader?

The engine sounds good, too, and refinement in the roomy cabin at cruising speed is fine.

Mazda is proud of its heritage for building cars that are fun to drive and, although the CX7 is never going to give an MX5 a fright on a testing B-road, it's impressive for an SUV.

The steering is light but there's more feel than you'd expect from a car in this class and the notchy gearbox shifts with accuracy. Mazda claims the chassis is now five per cent stiffer and new dampers help keep body movement in check. In fact, the CX7 felt more like a big saloon than an SUV - only the elevated view of the road ahead gave the game away.

There's only one model in the range and a single trim level (called Sport-Tech) which buys you leather upholstery, heated seats, satellite navigation which can find addresses with a full post code search and a premium nine-speaker Bose stereo with a fascia mounted multi- CD changer and Bluetooth mobile connectivity.

As well as the usual safety equipment there's also Mazda's rear-vehicle monitoring cam and an advanced blind spot warning which warns when a car has been detected coming up on your shoulder.

With that kind of specification the CX7 represents reasonable value for your £25k. A Ford Kuga is cheaper but it is also smaller and less versatile.

In some European markets the CX7 is offered with a choice of diesels with150 bhp and 180 bhp power outputs but, I suspect, demand will be limited in the UK so Mazda are playing safe with just the one model over here.

Running costs are a huge improvement over the petrol: the diesel returns 37.7 mpg (nearly 25 per cent more than the old CX7) and emits 199 g/km of carbon dioxide instead of 243 g/km.

Now Mazda has stopped trying to kid us that we need an SUV version of the MX5 it seems to me that the CX7 has come into its own as an interesting left-field take on the on-road SUV.

SPEC CHECK: Engine: 2,184cc turbodiesel Power: 173 bhp @ 3,500 rpm Torque: 295 lb/ft @ 2,000 rpm Top speed: 124 mph 0-62 mph: 11.3 seconds Fuel consumption: 37.7 mpg (official average) CO2 output: 199 g/km Road tax: £215 Standard equipment: Satellite navigation, electric mirrors and windows, power steering, six-speed gearbox, 19-inch alloy wheels, Bose setero, leather upholstery with electric front seat adjustment and front seat heaters, climate control, alarm, immobiliser, cruise control, reversing camera, split/fold seat.