Lurking underneath this test car disguise is a prototype of BMW’s new 5 Series, due in 2009.

Expect this incarnation of the large saloon to be much more conservative than it’s predeccessor, probably in line with the Concept CS unveiled last year.

Most of the exciting developments are likely to be under the skin, with particular focus on green efficiency and handling.

Sources hint at increased use of aluminium to keep the weight down, and standard fitment of Efficient Dynamics, the technology that cuts the engine when idling at standstill and disconnects the alternator when the battery is charged.