So why has BMW released details of its all-new 1-series – and even allowed a selected few journalists to drive it – months before the car's official release? Could it, perhaps, have anything to do with the fact sales of VW's fifth generation Golf are behind expectations in every major European market apart from the UK, where they're currently running 20% ahead of target?

Call me a cynic, perhaps, but in the brutal hand-to-hand compact that is the European C-segment market, the golden rule is never give your competitor an even break.

BMW and VW competitors? In the C-segment? You bet! BMW's all new 1-series, costing from about £16k when it arrives in the UK later this year, is aimed squarely at the new Golf. And although Golf will still probably outsell the new baby BMW by four to one, the 1-series is the most serious threat to VW's fabled cash cow in decades. Why? Because the 1-series wants to storm the premium small car niche VW has been assiduously grooming Golf for since the late 1990s, skimming the cream right off the top of the C-segment market.

That reason alone would arguably make the 1-series the most important small car of the past 30 years. But there's another – BMW has torn up the front-drive, transverse engine small car blueprint so eloquently defined by the original Golf 30 years ago, for the new 1-series features longitudinally mounted engines and transmissions, and rear-wheel drive, just like a 7-series. Sportier rear-drive is now at the core of BMW's carefully crafted 'Sheer Driving Pleasure' advertising tag line.

There was never any question the 1-series would be anything but rear drive. And it does handle beautifully, according to those who've driven the five-door hatch that kicks off what will be a five bodystyle range. But there is a compromise – poor rear seat legroom.

The thing is, that won't really matter. The 1-series recognises there are a lot of C-segment buyers who like a five door hatch but rarely use the rear seat. It also recognises there are also a lot of drivers who'll squeeze their passengers in the back seat if it means they can buy a BMW for Golf money.