THE notion of a 1.5-litre three-cylinder-powered 3 Series is about as appealing as a 6.2-litre V8 shoehorned in a Mitsubishi Mirage sedan. A Freaky Friday scenario of predictably B-grade results.

But bear with us, because what BMW has achieved with the reborn 318i sedan is nothing short of outstanding, particularly when you consider how impressive the existing (and previous) TwinPower turbo units have been in this generation sports sedan.

It’s the sheer business-as-usual normality that is perhaps the most startling aspect of it. Mated to a brilliant ZF eight-speed automatic transmission, the three-pot turbo 3 Series leaps off the line with unexpected enthusiasm, and then just keeps on powering on, seemingly oblivious to the F30’s substantial size and weight. It’s far, far from being underpowered.

Just as enlightening is the fact that the car’s occupants cannot hear the usual three-cylinder thrum that might be charming in something like a Fiesta EcoBoost, but out of character in a vehicle that – as tested on the roads around the Dandenong Ranges – topped $66K. There is a melodic upper-rev hum, but it sounds more high-tech than highly strung.

More pleasingly for enthusiasts, this diminutive drivetrain’s lightweight mass over the front axle seems to pay dividends in terms of steering feel (natural), cornering capability (sharp), and roadholding finesse (planted), falling in line with how we always imagined a sports sedan like a 3 Series to jive – that is, like a world-class figure skater with a wee bee under its bonnet… deliciously quick without being frenzied.

Since our example had so many options – including the absolutely necessary Adaptive M suspension that brings the essential adaptive dampers for a comfortable rather than punishing ride – it was hard to really assess the loaded 318i as an entry level entity, but the cabin architecture has stood the test of time well and the styling remains attractive.

However, things may change if seen through the prism of the stark Sensatec vinyl trim in the base $55K stripper special, even though there are actually plenty of standard goodies like sat-nav, 18-inch alloys, a head-up display and a few more besides.

So the facelifted base-model 318i has a sparkling can-do charm, helping boost what has been a pretty strong contender in the premium mid-size class.

Traditionalists may wince at the notion of such extreme downsizing, but the proof is in the driving.

And, for those who are too young or have forgotten their BMW history, until 2001’s E46 LCI facelift, the 318i was always the feeble laughing stock of the otherwise high-flying 3 Series range.

Happily, the three-pot turbo version joins the A-team.