The best car in the real world has just got better. Power boost puts it even more ahead of its peers

Amid all the hoopla surrounding the arrival of the latest 5-series, another crucial piece of new Munich metal is in danger of missing out on its much-deserved slice of the action. But we weren't about to let that happen to the revised 330d, an evolution of one of the most significant cars of recent years.

We'd met the quick diesel breed before, of course - BMW's own 325tds had fired our imagination nearly a decade earlier. But three years ago the original 330d took the concept to an altogether different plane, with an astonishing blend of 140mph performance and 40mpg economy.

Now the baby Three has inherited the 730d's more advanced common-rail 3.0-litre six. Although the 330d doesn't quite get the Seven's full 369lb ft of torque, figures of 204bhp and 302lb ft are still damned impressive and represent useful hikes over the old car's 184bhp and 288lb ft tallies.

The factory performance numbers say top speed is up 8mph to 149mph and the sprint to 62mph drops by 0.6sec to 7.2sec (high sixes in Autocar money), but even they don't adequately describe the fireworks that a twitch of the right toe can ignite.

Try lugging from under 1000rpm in the tallest cog in most four-pot turbo-diesels and the engine is likely to stall in response to your stupidity. Select sixth in the 330d, noticing the new car's extra gear as you do so, and there's not even a murmur of discontent. You still feel the extra torque come on board at 1500rpm in each gear but it's a progressive shift and the power doesn't tail away until the rev limiter spoils your fun at 5000rpm.

Despite the greater performance, combined fuel consumption drops slightly from 43.5 to 42.2mpg. Unfortunately the new engine won't meet Euro4 emissions regulations until BMW attaches a particulate filter next year. For now, the 330d will still be subject to a three percent company car tax loading. This means drivers will be taxed at 22 per cent, although that still represents a significant saving on the petrol 330i at 26 per cent.

When a 320d performs so strongly on so little fuel it might seem difficult to rationalise spending an extra £4610 on its bigger brother. But it'll only take a couple of miles to convince yourself otherwise.

Chris Chilton

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