HAS it really been four years since we first drove the current-generation 3 Series range?

During that time we have had newcomers from Lexus, Mercedes-Benz and Audi, and the latter two have really moved the game on in interior presentation and ambience compared with the BMW.

But the Bavarians have always had their ‘Ultimate Driving Machine’ mantra up their corporate sleeves to fall back on, so the 3 Series has always redeemed itself against the fresher foes once you factor in the driving bit as well.

These days, however, low fuel consumption and emissions seem to be the name of the game as far as the Europeans are concerned, so out comes a raft of 3 Series diesels spouting BMW’s EfficientDynamics logic to lure the more conscientious motorists among us.

And you cannot argue with the raw figures, since every 3 Series rival suffers in comparison when power, torque, performance, fuel consumption and carbon dioxide ratings are taken into consideration.

Plus, every one of these new-fangled diesel BMWs we drove were true to the brand’s core in driving pleasure. None felt compromised for being greener.

In the case of the 320d Touring, it is all the BMW wagon you could possibly want, making the petrol engined 320i, 323i and (fabulously fast) 335i Touring variants seem obsolete.

Step-off acceleration is strong, the engine feels revvy and alive, and the six-speed automatic gearbox is a well-chosen mate, providing the right gear at the right time without fail.

On the other hand, the E91 wagon as a load carrier is not the roomiest wagon on the market.

And we didn’t sample it in urban situations (to test the firm ride that has mars so many big-tyred German cars sold in Australia), or fully laden, but the levels of refinement and noise suppression seemed more than a sufficient.

Then we had a go in the 330d Coupe and 330d Convertible, and again the effortless forward thrust that 520Nm of torque provides proved quite persuasive.

The 3.0-litre diesel feels like it could power its way though any situation, to the point where you wonder if there isn’t too much torque on tap. But that’s crazy talk, because the resulting engine response makes this BMW a bewilderingly quick point-to-point machine.

The 330d Convertible’s hefty 200kg-plus weight deficit probably makes going for the big diesel six in the sun-worshipper version the more logical choice than the petrol ones, since this is the only model in the retractable hardtop range this side of the M3 that does not feel a little let down by all the lard it accumulates.

Add in the fact that BMW has done a fine job keeping the diesel noise outside of the car, and the case for the big diesel convertible should be sealed if you’re in the market for such a car.

But the 3 Series as a range is looking a little stale in that rather austere cabin – there’s just too much hard shiny plastic about the place to make the occupant feel as if they have bought premium.

Yet no rival to this day is as involving to drive (though most ride better, we must hasten to add), so there is no real alternative if you want your diesel to feel like a BMW from behind the wheel.

What’s the bottom line then? It is the oily bits that are keeping the ageing 3 Series fresh, and the diesels are as worthy as any (non twin-turbo or M GmbH modified) petrol unit.

So you can go green with glee!