The New Z4 Roadster
Published: 23rd June 2003
Keeping the Z4 on the straight and narrow is BMW’s Dynamic Stability
Control (DSC). Activated when the car begins to lose grip and threatens
to slide, it reduces power to the driving wheels at a 5 per cent loss
of traction. In extreme circumstances, the system applies the brakes
to get the car, and driver, out of difficulty. The Z4 also features
Dynamic Traction Control (DTC), maintaining driver involvement in
tricky conditions. Activated by turning DSC off, DTC provides the
same fundamental reassurance as DSC, but with a greater threshold
of 10 per cent loss of traction. The combination of the two gives
the driver the safety and security provided by DSC with the same nimble
agility of a car equipped with a conventional limited-slip differential.
Customers can also specify the optional five-speed automatic gearbox featuring Steptronic manual shifting, carried over from the 3 Series range, or BMW’s latest six-speed Sequential Manual Gearbox (SMG). Featuring shift-by-wire technology, the driver can change gear seamlessly either using steering wheel mounted F1-style paddles or the reassuringly stubby gear lever. Gear change and clutch actuation are controlled by gearbox electronics and a hydraulic system, allowing the driver to ‘flat change’ in lightning gearshift times of 150 milliseconds, with absolute precision and consistency. Flattering those who haven’t quite perfected the art of ‘heel and toe’, the system will blip the throttle to deliver perfect down changes, matching engine speed with the selected gear ratio.
The SMG system also has a full-power acceleration mode in its armoury. With DDC activated by pressing the Sport button and subsequently deactivating DSC, the engine’s full power is unleashed when the rev’s reach 4,000rpm and the system ‘dumps’ the clutch, guaranteeing the Z4’s 0 – 62mph sprint in 5.9 seconds. For those appreciating the system’s full flexibility, SMG also has a Drive mode, acting effectively as an automatic.
Transmission
Every driving style is catered for, as the Z4 is available with four gearbox combinations. The 2.5i roadster comes as standard with a five-speed manual gearbox, whilst the 3.0i has the new six-speed manual gearbox introduced recently on 3 Series Coupe and Convertible models.Customers can also specify the optional five-speed automatic gearbox featuring Steptronic manual shifting, carried over from the 3 Series range, or BMW’s latest six-speed Sequential Manual Gearbox (SMG). Featuring shift-by-wire technology, the driver can change gear seamlessly either using steering wheel mounted F1-style paddles or the reassuringly stubby gear lever. Gear change and clutch actuation are controlled by gearbox electronics and a hydraulic system, allowing the driver to ‘flat change’ in lightning gearshift times of 150 milliseconds, with absolute precision and consistency. Flattering those who haven’t quite perfected the art of ‘heel and toe’, the system will blip the throttle to deliver perfect down changes, matching engine speed with the selected gear ratio.
The SMG system also has a full-power acceleration mode in its armoury. With DDC activated by pressing the Sport button and subsequently deactivating DSC, the engine’s full power is unleashed when the rev’s reach 4,000rpm and the system ‘dumps’ the clutch, guaranteeing the Z4’s 0 – 62mph sprint in 5.9 seconds. For those appreciating the system’s full flexibility, SMG also has a Drive mode, acting effectively as an automatic.
