Long bonnet, short overhangs, low centre of gravity, soft top: the sporty two-seater doing its laps at the BMW test centre in Miramas in the south of France is instantly recognisable as a roadster.
It is the new Z4 which is currently undergoing another important stage in the process towards serial production, in this case involving testing of the driving dynamics of a heavily disguised prototype. This will provide the manufacturer with key insights into the performance properties of the new model.
Trials at the Autodrome de Miramas are focusing on fine-tuning all of the drive and suspension systems – the basis for the ‘sporty driving experience’ offered by the latest Z4. The most intense form of the roadster is embodied by the M40i variant, which boasts a new, “extremely powerful” in-line 6-cylinder engine, a lowered sports suspension with electronically controlled dampers, a newly developed front axle, M light alloy wheels with mixed tyres, an M sports brake system and an electronically controlled lock in the rear axle differential all of which create an overall package that “sees the BMW M Performance model setting a whole new benchmark for driving pleasure in the roadster segment” according to the makers.
“The vehicle concept of the new BMW Z4 is geared consistently towards agility and driving dynamics” explains Jos van As, Head of Application Suspension. “The high level of body stiffness and the very rigid suspension attachment provide the perfect basis for a set-up that guarantees the performance qualities of a genuine sports car in terms of steering precision as well as longitudinal and transverse acceleration.”
The Miramas test centre offers perfect conditions for trials; it has been used by BMW to develop and test new models for more than 30 years.
The centre comprises a long asphalt oval and a motorway ring road for high-speed tests as well as slalom, serpentine and circular tracks and a number of handling courses and circuits featuring highly diverse types of surface. These are currently being used for detailed analysis and optimisation of the roadster’s acceleration, steering and brake response.
This intense testing process already indicates that the new version of the Z4 roadster concept will offer a tangible increase in what BMW calls “sporty flair”. The new generation will particularly introduce “effective enhancements in terms of agile handling, spontaneity and precision when changing direction and accelerating in dynamic style out of bends – without losing out on comfort”.