CONSIDERING how long ago 1975 was, it comes as a bit of a shock that we have had only five 3 Series generations since then.

The world is almost unrecognisable since the year Countdown started and the Vietnam War ended for Australians – but the essence of the smallest four-door five-seater BMW has remained the same.

Now, born for a sixth time, can the 2012 F30 model continue the model’s legacy as the default sports sedan?

Part of what has changed over 37 years has been the 3 Series’ competition, for all have aspired to be perceived as dynamic as the Munich machine, to varying degrees of success.

Of all its rivals, perhaps the existing Mercedes C-class has come closest. We rate it as a more complete overall package, a fact borne out of the Benz’s top-selling status.

It’s important to keep this in mind because the F30, conversely, attempts to be a more rounded proposition, just like its nemeses.

Proportionally, the freshest BMW is slightly bigger for improved interior space – eroding one of the Audi A4’s strong points the styling is sleeker and more shark like … Italianesque even (in a Maserati Quattroporte fashion around the bull-nosed bonnet treatment), to perhaps persuade Alfa people.

The new Modern personalisation pack and its blonde woods have a distinct Scandinavian feel, a concerted effort has been made to match the Mercedes in terms of ride comfort, and raising the specification list while dropping prices (on some models) appears to be a Lexus and Infiniti way of doing things.

For all these reasons, then, the latest 3 Series is a palpably more complete car than its predecessor. The styling is more interesting, the cabin looks and feels more upmarket, and the rear seat and boot offer more room.

We are especially enamoured by the seats, intuitive iDrive vehicle controller, driving position and general overall ambience.

Mind you, a piece of plastic windscreen pillar trim came adrift in our hands (and contributed to some very noticeable wind noise as a result), so maybe there’s still work to be done.

But none of this answers what must surely be the crux of any BMW experience –is the F30 a better drive than its E90 predecessor?

At the Australian launch in Melbourne’s beautiful Healesville region on a gloriously warm and sunny St Valentine’s Day, we sampled a $61K-plus 320d, $67K-plus 328i and $92K-plus 335i to find out.

And what we experienced was three different variations on the same 3 Series theme.

Least excitingly but most relevantly, the expected bestseller 320d (in racy Sport line) is a smooth, swift, and sparkling example of how accomplished diesels have now become, thanks to determined acceleration, sufficient drivetrain quietness, and some startling economy and emissions figures.

Armed with the standard eight-speed automatic transmission (complete with paddle shifts) and a four-mode driving choice (Eco Pro, Comfort, Sport and Sport Plus), the more powerful of the two diesel options (the 318d is the entry level F30) has an astounding breadth of capability that should satisfy consumption-conscious driving enthusiasts for years.

Even only after a couple of hours behind the wheel. that old cliché about ‘all the car you’ll ever need’ kept springing to mind. Or perhaps we ought to reserve that for the upcoming wagon version?

Back in the here and now, in Comfort mode, we suspect a C-class might have the edge on suspension cushioning and road noise suppression, but the BMW sedan has taken massive strides to close the gap indeed, in most other ways behind the wheel, the newcomer’s sharp and linear steering, balanced chassis feel and surefooted body control appears to put clear air between itself and the other combatants.

We are a little underwhelmed by the sameness of the F30’s cabin’s similarity to other Bimmers like the 5 Series’, and the Sport mode’s (thankfully optional) dark hues and garish red trim is very much an acquired taste, but – again – real progress has been made over the preceding version. We like.

Next up we sampled the (for now) range-topping 335i, brandishing the only straight six-cylinder engine on offer. Marque tragics commit Hare Kari now.

With twin-turbo technology and a treacly slickness that needs to be driven to be truly appreciated, this car is a devastatingly rapid point-to-point sports sedan in the truest tradition it leaps off the line with forceful intent, maintains the rage right up the sweet rev range, and sounds sublime doing so.

Phenomenal grip, aligned with planted yet pointy steering, are further plus points, particularly as this model has the instantaneous momentum to make the driver feel like he or she can power out of virtually any situation. Family needs prevent a Porsche Cayman PDK parked in your driveway? Please consider this instead.

Yes, there’s a bit more road noise in the 335i, and the ride quality is best described as acceptable (there’s pitter-patter busyness in places), but the blown six Bavarian bahn botherer has the muscle and the moves to make you reconsider that 5 Series, A6 or E-class of similar money.

And then we sat behind the wheel of the 328i – an evocative nameplate as well as a deceiving one.

Some might think it sacrilegious that BMW has elected to go with four rather than six cylinders, after the history and glory that this set of alphanumericals conjure up but the turbo-charged four-pot mid-ranger is the absolute riot of the F30 clan.

Rorty down low, fervent up top, this M20-series engine firecracker belies the length (and bulk) of what is a largish medium-sized sedan, to provide boisterous step-off performance or calm-blue-ocean smoothness and serenity – the choice is all up to you.

Here is where chassis balance and harmony come together with hammering acceleration (in Drive Sport with the Sport Plus activated), to create a blend of Golf GTI alacrity and Mercedes-Benz refinement. There’s no other word to describe what BMW has achieved – the 328i nails it. This F30 more than any other elegantly and eloquently underlines why the 3 Series has once again become the best in the business.

OK. Enough praise and time for a reality check. Fabulous sweeping mountain roads are one thing, punishing urban roads are another more time in every new BMW 3 Series is essential before a definitive verdict can be reached.

And yes, more value has been injected in the range, but desirable options remain expensive despite sub-7.0L/100km luxury car tax-related price drops, while high servicing and maintenance costs are still an ongoing wallet walloper for any German luxury car buyer.

But in 2012, the sixth-generation 3 Series is now one of the most desirable sports sedan in its class in the world – as well as the most complete in the nameplate’s 37 years.