If all diesel engines were created equal and could be measured solely on their figures, the 148bhp variant found in the Volvo V40 D3 would appear to be perfectly suited to the 21st century business of propelling a hatchback around promptly and economically.
A sub-9.0sec 0-60mph time and a 45.9mpg overall economy figure attest to that. The five-cylinder unit likes to warble but, at 68dB at 70mph, it is not intrusive or unpleasant.
But there are issues, chiefly with the way the V40 delivers its power. The D3 may develop all of its 258lb ft of torque at just 1500rpm, but it idles at 720rpm and the six-speed manual gearbox has a habit of repeatedly stumbling on the 780rpm of lethargy in between. Typically, this occurs when ambling slowly around residential street corners in second or third gear.
An impatient driver (or, indeed, anyone concerned with forward motion) will attempt to remedy the chronic lag with a more aggressive stab of the throttle, leading to a sudden rush of energy as the engine – or, more precisely, its turbocharger – catches up with your intentions. Spend too much time turning in and out of tight junctions and the D3’s driving experience comes worryingly close to tiresome.
Moreover, the other diesels seem afflicted by similar traits; the 325lb ft of the D4 we also tried recently arrives in a great stampede between 1750rpm and 2750rpm. Its gear ratios compounded the problem, often dropping the engine into its frustratingly unresponsive zone below 1500rpm. The 114bhp D2 model is also a reluctant performer at low revs.
The D3 is much improved once it has been unfurled out of town. Peak torque is tapped out by 2750rpm, but more often than not you’ll have been pulled promptly beyond the national speed limit before needing to sidle into the in-line five’s reverberant high revs. It’s a strong performer on the motorway, too, where a long sixth gear chimes perfectly with all the available tug at cruising speeds. Just don’t try merging in top; 30-50mph takes an agonising 20.9sec.
A pair of 1596cc turbocharged fours comprise the petrol engine line-up. The D3 develops 148bhp at 5700rpm and 177lb ft from 1600-4000rpm, while the 178bhp D4 sees the same amount of torque stretching to 5000rpm. The results are a 0-62mph time of 8.8 and 7.7sec respectively, while top speeds are 130 and 140mph.