As concepts go, few things sound more incorrect than a diesel-powered Alfa Romeo. Yet it was Alfa Romeo which ushered in the technology behind most modern turbodiesels when it launched the 156 JTD seven years ago.
Today almost all diesel cars use common-rail systems, where fuel is delivered from a common fuel rail and injected into the cylinders at massive pressure. But now Alfa Romeo, together with parent company Fiat, is pushing through the next generation of common-rail Multijet diesel engines.
The 147 JTD 16v employs this technology: unlike normal common-rail engines, the Multijet squirts several small shots of fuel into the cylinders to promote better combustion.
The original 1.9-litre block is retained but undergoes some serious surgery, gaining four valves per cylinder, an extra camshaft and new intake and exhaust manifolds, while injector pressure rises from 1300 to 1400 bar. The resulting figures – 138bhp at 4000rpm and 225lb ft at 2000rpm – show a useful improvement over the single-cam JTD’s 113bhp and 203lb ft.
That’s more twist than the 247bhp 147 GTA produces; although it’s more relevant to point out that it also out-torques the 184lb ft of the cheaper Ford Focus TDCi and similarly priced Audi A3 1.9TDi.
That’s an advantage that counts on the road and the JTD 16v feels far faster than its 9.1sec 0-60mph time suggests. And unlike VW’s quick but inflexible PD150 Golf, the Alfa isn’t saddled with a powerband the width of a gnat’s G-string.
There’s usable power at 1500rpm but the revelation is that the real action, which arrives at two grand, is sustained until the red line 2000rpm later. It stays smooth and refined too.
Modern diesels can be fun but they still need to make sense, too. Compared to a petrol 147 the JTD succeeds, achieving 47.9mpg on the combined cycle, although the more basic single-cam JTD is more frugal by 1mpg.
And while the 157g/km of CO2 it produces looks impressive, it doesn’t comply with Euro4 emission regulations so company car tax payers still suffer a three per cent surcharge.