There is real innovation in the Mazda CX-5 SUV but its design makes it look a bit of a frump

How Mazda slimmed down to come up with a hybrid-beating SUV.

Price: From £22,995
Engine: 2,191cc, four cylinders, 16 valves, twin-turbo diesel, 150bhp
Transmission: Six-speed gearbox, front-wheel drive
Performance: 126mph, 0-62 in 9.2sec, 61.4mpg, CO2 119g/km

We'll cut straight to the chase here. This particular chase is for the patch of blue sky above the Scottish mountains I am driving past, hoping to keep ahead of the towering storm clouds behind – and the car is doing something I have not known a diesel production car do before.

As I accelerate through the gears, the engine seems happy to spin ever faster. Only at a vigorous 5,800rpm does the power delivery cease its build-up, yet it has been coming on strong from as low as 1,000rpm. This is an extraordinary range of usable power for a turbodiesel, all of it delivered more crisply and smoothly than it is by many a petrol engine.

The new CX-5 SUV is Mazda's first car to embody the whole gamut of its new Skyactiv Technology. The philosophy is based around the saving of weight, the reduction of friction and the efficient use of fuel, and is touted as a simpler, cheaper alternative to hybrid drivetrains.

At its core, in the engine at least, lower combustion temperatures greatly reduce the harmful particulates and nitrogen oxides in the exhaust, and by injecting the fuel early in the combustion cycle, the expansion of the burning fuel-air mixture can apply its force for a longer time without the percussive explosiveness usually felt in a diesel. This means the engine's components can be less massive, saving weight. Less weight allows other components – gears, brakes, suspension arms – also to be less massive, so less energy is needed to move them. Brilliant.

It would have been even better if all this technology had been installed in a car with looks to match, but this hasn't quite happened. The CX-5's style, with its bluff, protuberant nose and what looks like the aftermath of off-road contact along the flanks, accords to Mazda's "Kodo" design, but this waft of otherness is to be short-lived. The next Mazdas will look crisper and less melted, and no doubt will bear the tag of another Japanese visual expression.

The roomy interior is similarly uninspired, although neat enough, and there's the now-usual display screen with Bluetooth and iPod connections. All CX-5s come with satellite navigation to begin with, but once the launch stock is sold it will be an option on the lower (SE-L) trim level. This, in many ways, is the more sensible version to buy because it still has as much equipment as you can reasonably want, and it runs on 17in wheels instead of the higher-trim Sport model's 19in wheels. The latter make the ride more fidgety over bumps yet don't make the steering's responses crisper.

Being an SUV, the CX-5 can be had with four-wheel drive. You pay for the greater chance of getting up a slippery hill with slightly worse performance and economy. The 165bhp petrol engine comes with front-wheel drive and a particularly slickly shifting manual transmission; the two diesel engines' outputs bracket this figure with 150bhp or 175bhp, and a very responsive six-speed automatic is also offered here. Clearly, the higher-powered diesel feels livelier, but it can be had only as a Sport-trim 4x4 with a 136g/km CO2 figure – impressively low, but not as remarkable as the front-drive, 150bhp car's 119g/km.

That's the one I would have, in SE-L trim (who really needs leather upholstery, after all?). The lower-power diesel is even smoother than the full-fat one, and the whole car feels wieldy, precise and supple in ways not always encountered in compact SUVs. What's more, its green halo glows much the brightest. There's real innovation here. I just wish it looked less of a frump.

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