It may be a staple on our roads, but you should never let familiarity lull you into underestimating the importance of the 3 Series to BMW.

The 3 Series has been a best-seller in its class for 40 years, during the majority of which time it has been regarded by our independent tests as a class leader, and it accounts for a quarter of all of the company’s global sales.

That’s why today’s reveal of the facelifted model had more than the usual frisson of excitement about it. Top of the tree in terms of sales it may be, but there’s no question that the 3 Series is under attack from all sides: Mercedes claims a better interior, Jaguar better dynamics and Lexus the better hybrid options. Audi, meanwhile, has a new A4 on the way.

At today’s launch BMW’s British head of sales and marketing, Ian Robertson, acknowledged as much, albeit obliquely, when he said: “The 3 Series has always been the benchmark - and that means it is the car competitors scrutinise when they look at how they can improve. We intend to maintain that status now and into the future.”

Tweaked rather than redesigned this updated car may be, but the facelifted 3 Series promises dynamic, efficiency and technological strides that do more than enough to keep it at the cutting edge.

Already, the option of a 99g/km automatic BMW 320d ED will be tugging at the consciousness of company car buyers pulled towards the similarly efficient but manual gearbox-equipped Jaguar XE.

What’s more, this is just the start for BMW. Next year, frugal three-cylinder engines and a 49g/km plug-in hybrid option will go on sale, and BMW promises more updates ahead of an all-new car launching around 2018, when you suspect that the proverbial kitchen sink will have been thrown at settling any advances made by potential upstarts.

Make no mistake, BMW isn’t going to relinquish its advantage lightly - and its rivals aren’t going to stop striving to eclipse it. That’s why the compact executive battle is so exciting - and why the overlap of current development cycles between the main competitors means it will be a battle that remains fascinating to watch for years to come.

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