Innovation is driving Volvo's current good fortunes and a new range of D4 turbo diesels is its latest venture. Iain Dooley, of the Press Association, puts it to the test.

The last few years have been interesting for Volvo. From being part of the mighty Ford empire to being snapped up by a Chinese corporation, the Swedish car-maker has had to learn to become more independent and agile in an increasingly-crowded market.

The notion of independence has included developing more of its own technology and engines since it cut the cord with Ford. These things take time, and it's now that we can see the fruits of its labours.

Focusing on the increasingly-important issues of emissions and economy, Volvo's decision to go down the four-cylinder diesel route isn't surprising. Its promise of the usually unobtainable high power and reduced noise is, though.

These new in-house developed and produced turbo diesel engines promise to give the likes of BMW, Audi and Mercedes-Benz a few sleepless nights – exactly the brands Volvo seeks to challenge.

Fitted to the company's fleet-friendly S60 saloon, the new 2.0-litre D4 motor boasts 181 horsepower and, crucially, emits only 99g/km CO2 plus offers a combined economy figure of 74.3mpg.

You might think that Volvo's decision to base its future on four-cylinder engines is a risky one, but the reality is very different. Clever engineering and the desire to simplify its line-up has resulted in a package that's equal to and in many cases better than the competition.

On the road, the S60 delivers a refined, quiet and polished driving experience that is on par with the best Germany has to offer. The Volvo engineers' efforts to banish unnecessary noise and vibration from the cabin has been successful, with the car delivering a smooth, rattle-free performance.

To complement the new engine range Volvo has introduced a new six-speed manual and eight-speed automatic gearbox option. The former is much improved over its predecessor, with the latter proving pleasingly responsive and predictable in a range of driving environments.

While these engineering changes are a big deal, the rest of the S60 has remained the same as before. Far from being a bad thing, the car's soft curves, practical saloon shape and driver-friendly cabin help set it apart from its often more clinical rivals.

And if you're keen to stick with the business-user theme for the D4-powered S60, the generous level of standard equipment, plush interior and practical cabin and boot space should take the edge of those long, dull y journeys on the motorway.

All in all, the updates to the range have done a great job of boosting the S60's appeal, which is vitally important if the car is to compete head-on with the more established competition.