The most recent major technical change to the enormously successful Nissan Qashqai crossover SUV was the introduction, late in 2011, of a new 1.6-litre dCi turbo diesel engine. Devised by Nissan's alliance partner Renault, it produces a maximum of 128bhp, and by current standards that's a very high figure of a diesel of this size. But the real benefits can be found in the fuel economy and CO2 emission figures.Including stop/start (which was not available on the earliest models to use this engine), a 1.6 diesel Qashqai achieves 62.8mpg on the official EU test, while its CO2 rating is just 119g/km. No other Qashqai comes close to these figures, nor to the mere £30 you'll be asked to send to the Exchequer each year in the form of Vehicle Excise Duty.There's more to this than running costs, though. This is an engine that suits the Qashqai very well. It's reasonably quiet, with almost none of that characteristic diesel rattle, and while you can certainly buy a faster Qashqai I wouldn't personally feel the need for much more straightline performance than this one provides.The 1.6 dCi has all but destroyed the case for the slightly smaller and much older 109bhp 1.5-litre diesel engine which is still available in the range. There was a time when I would not have bought a Qashqai fitted with anything else, but that was in the days when Qashqai handling was very suspect, and the appeal of the 1.5 lay largely in the fact that it didn't have enough power to cause the chassis any trouble. The suspension revisions Nissan introduced in 2010 took away that advantage.Strangely - and this may show up the anomalies of the official fuel testing process rather than representing real-life conditions - the 1.5 is also, on paper, much less economical than the 1.6, and its 137g/km CO2 emissions mean that annual VED payments are nearly four times greater than that of the 1.6 at £115.Then again, the 1.5 is £1500 cheaper, and it may appeal more to people who never drive over long distances and don't cover many miles in the course of a year. But if you did that you might be better off with a 1.6 petrol Qashqai, which won't have a great resale value but will be much cheaper again to buy in the first place.The test car was an n-tec+ with 215/55 tyres on 18" alloy wheels. That set-up, if I'd checked it before driving rather than after, might have led me to be fearful about the ride quality, but in fact it's decent enough, with only some minor jiggling over small bumps.Other n-tec+ features include Nissan's Around View Monitor, which gives a 360-degree view of what's near the car in parking situations and goes some way to addressing the Qashqai's visibility problem. But I still wish it had decently-sized rear windows.Luggage capacity of the Qashqai is 410 litres with the rear seats up and 860 litres with them down. Judging by the sales of the car, it seems to be enough for many people, and for those who want more there's the Qashqai+2 (also available with the 1.6 dCi engine), which is longer and roomier and can hold up to seven passengers.The Qashqai hasn't been through a Euro NCAP crash test since 2007, but back then it achieved what was at the time the highest-ever score for adult occupant protection. Euro NCAP has revised its testing procedure in recent years, and it would be interesting to see how the Qashqai would do now, though I imagine it would still perform pretty well. Engine 1598cc, 4 cylinders Power 128bhp Transmission 6-speed manual Fuel/CO2 62.8mpg / 119g/km Acceleration 0-62mph: 10.3 seconds Top speed 118 mph Price £23,145 Details correct at publication date