It's not going to light the fire of desire in your nether regions, but Vauxhall's seven-seat Zafira is one of the most practical and flexible cars on the road. Sales figures prove its popularity – nearly 48,000 were sold last year and it can't be for nothing that it's by far and away the best-selling vehicle of its kind in the UK.My test car is a 1.9 CDTi in Design specification. It's a five-door compact multi-purpose vehicle that shares much of its gizzards with its hugely accomplished sibling, the Astra. Design level of specification is around the middle of the ladder.There are two 1.9-litre turbocharged diesel engines in the range - this one is the more powerful version with 148bhp on tap and 236lb/ft of torque. Pumped through the six-speed gearbox to the front wheels, that's enough to pull the 1.5-tonne people carrier up to 60mph in 10 seconds.Vauxhall tells us with a perfectly straight face that the Zafira has "sharp styling" that's "definitely got the X-factor". Well this year's facelift has certainly turned it from a worthy-but-ugly geek into something resembling a real car, but the plain truth is it's really just a box with a bonnet. It's tidy, it's clean and it looks no worse than the competition, but the only heads it will turn are those on the buttercups that nod in the slipstream as it passes.With this in mind, I wasn't expecting to be stirred much when I got into the driving seat. Gazing around the roomy but tasteful interior, with perhaps rather too much black plastic trim, I was getting my mind into the space occupied by a steady-away family guy who's wanting to carry all his precious little eggs in one big, safe, efficient basket. But it was on the hill up towards the Scord of Tresta on Shetland that my perception changed somewhat.It's a long steep slope up the side of the valley that can bring a fit of asthma to many well-meaning motors, but as I stepped down on the go pedal, the Zafira just kept on pulling away. Changing to fifth was impressive enough, but getting up into sixth and still having torque to keep accelerating is what put the smile on my face.The game plan changed from that point on. Pushing out a little harder now, I found this 1.6-metre tall vehicle handled like a saloon or hatchback. Corners came without any drama whatsoever, the steering was sharp and the brakes on this fairly new car were almost too good. There was a bit of road noise, but the diesel engine was extremely quiet and wind noise was negligible.Worthy of note is the unobtrusive Sport button on the dash that does three things for you. Stab it with a digit and you get "sports performance" which means sharper throttle and more responsive steering. Drive along at a constant speed then push it and the whole car surges forward like it's been fed a can of Red Bull. I said it did three things though, and the third is that it makes a serious dent in your fuel efficiency if the onboard computer is to be believed.Normally this engine is very efficient - it will give you an official average of just over 46 miles per gallon, and while the driver before me had been getting a rather less impressive 38mpg, I was able, over the space of a hundred miles or so, to bump that up to around 50mpg. It's not quite the number that's its theoretical best, but I was taking in a lot of hilly countryside and country roads rather than gently sweeping motorways. Yes, I was impressed.Now with renewed enthusiasm, I looked around the driver's environment a bit more appreciatively. The stubby gearstick on the buttress protruding from the centre console was a nice effect, and introducing a hand-brake that looks like an aircraft cockpit control is a nice touch, even if it's a little clumsy to operate when the central armrest is down. Visibility all round is good but the fat A-pillars need a bit of looking around at times in town or heavy traffic.I've never been a fan of the recentring indicator stem that nudges the flashers into action until the self-cancel or you nudge them off again - but I'm told you can get used to them.So what about the load-lugging options? Well, with all but the front two seats folded away, there's a massive cargo space in the back - tall, flat-bottomed and square. The second row of seats unfolded into place will comfortably take three adults in roomy comfort and still leave you a reasonable sized boot.When you need the very back two seats up, you slide row two forwards as far as it'll go, then go round the back, grab the handles in the boot floor, give them a tug and the chairs appear up out of the ground like magic – two good seats for youngsters, both with three-point seatbelts. The whole effect is only slightly let down by the low-tech folding concertina floor lining that's laid with no more finesse than putting down a stiff picnic blanket.The Zafira Design with this engine costs £20,885 on the road and industry pundits believe it will hold up to half that value after the first three years, much better than the petrol models.While you may not get a case of lust at first sight, at a time when the cost of fuel is going up beyond the dictates of logic or reason, solid and reliable transport with a fuel-efficient engine is increasingly becoming something you can learn to love. I'd say there's a very good reason why the Zafira is such a market leader. Engine 1910cc, 4 cylinders Power 148bhp Transmission 6-speed manual Fuel/CO2 45.6mpg / 167g/km Acceleration 0-62mph: 9.7 seconds Top speed 126mph Price £20,885 Details at publication date