It was inevitable that the quest to make the Z4 more comfortable would also make it bigger.
Although the two-piece aluminium roof weighs only 30kg, the car’s kerb weight has increased by 185kg over that of the previous-generation Z4 3.0si, and it has grown by 148mm in length and 9mm in width.
Despite the extra weight, the Z4 maintains its (as tested) 50/50 weight balance and improves upon its predecessor’s green credentials.
Although it doesn’t yet feature the stop-start system often integrated with BMW’s EfficientDynamics system – this will be introduced in the next 18 months – much of the system’s technology appears on the new Z4.
An intelligent alternator saves fuel by charging the battery during braking or only when it is required rather than constantly (as with a traditional alternator).
Electric power steering also uses 90 per cent less energy than conventional hydraulically assisted steering. As a result, the sDrive23i and 30i manage a combined 33.2mpg and 199g/km, while the manual 35i claims 30.1mpg and 219g/km.
Our sDrive35i test car was fitted with the optional double-clutch seven-speed auto (available on the 35i only), which further improves the claimed economy and CO2 output.
Safety provision has also been improved. The bodyshell of the new Z4 is 25 per cent stiffer than its predecessor’s, to the benefit of handling as well as crash protection, and the standard-fit Dynamic Stability Control + now offers brake pre-tensioning, whereby the brakes are primed electronically if the driver lifts off the accelerator sharply in preparation for an emergency stop.
