What is it?
BMW’s 2-series Active Tourer comes with the choice of both three-cylinder and four-cylinder engines, and now it also comes with the choice of front-wheel drive or four-wheel drive. This is the all-wheel-drive model, hooked up to a punchy 188bhp 2.0-litre, four-cylinder diesel engine.
BMW says the all-wheel drive system is based on the familiar Haldex clutch mechanism, which is mounted on the side of the gearbox and – when activated – sends power and torque to the rear wheels.
However, the company says it has modified the standard-issue Haldex unit to incorporate what it calls an "efficient valve". This is, in effect, a spring-loaded valve, which helps to control the oil flow to the Haldex’s clutch plates. The speed at which oil can be released to flow between the clutch plates governs how quickly the clutch pack locks up and then diverts drive from the engine to the rear wheels.
Even thought the latest, fifth-generation Haldex unit is by far the quickest-reacting version yet, BMW says its modification makes its version of this familiar all-wheel drive system is faster still. The Active Tourer's rear differential also has its own electronically controlled clutch pack, which has to be activated to get drive to the rear wheels.
The combination of these two high-speed clutch packs, say BMW engineers, marks the Active Tourer’s all-wheel drive system out from other, ostensibly similar 4x4 conversions of front-wheel-drive cars. BMW claims the all-wheel drive mode can kick in in just 0.1sec and it is active in most driving situations, rather than just in extreme conditions or after traction has been lost.
That means the xDrive Active Tourer will deploy four-wheel traction even on winding country roads, at motorway speeds and when cruising at lower speeds. As pointless as this sounds, splitting the engine’s effort between both axles should always pay dividends in terms of driving dynamics, even at lower speeds.