Flexibility is a hallmark elsewhere in the Z4 as well. A console-mounted switch toggles among three settings: normal, sport, and sport-plus, effecting changes in the steering effort, in throttle mapping, in the shift logic of the automatic transmission, and in damper firmness. (The latter is only for cars equipped with M Adaptive damping, part of the sport package, which also includes sport seats, eighteen-inch wheels, and a more generous electronically limited top speed of 150 rather than 130 mph.) This is a further evolution of the optional Sport button in the previous Z4, which affected throttle, steering effort, and automatic transmission shift control.
Carmakers' attempts to create electronics-induced multiple personalities have become increasingly widespread, but we find that they're often of little value. In the case of the Z4, the range from normal to sport-plus is pretty narrow. The difference in throttle mapping, for instance, is barely discernable, although that's rather a blessing since a hypersensitive gas pedal does not make a responsive car.
The change in steering effort is more notable, switching from too light to just right - but we'd happily do without the former. The steering is again electrically assisted (although the M Roadster used hydraulic assist), and it's certainly precise but lacks that last measure of tactility.
With regard to the transmission, we ended up preferring the less aggressive modes. All are responsive to a quick stomp on the throttle, but in sport-plus, the gearbox is so reluctant to upshift that you end up cruising around in fourth gear when a mellower mode would select seventh.
The selectable damping is a new feature with this redesign. Again, the difference between the different modes is subtle. But when driving hard, you appreciate the extra control of body motions (primarily pitch and dive) offered by sport-plus, which combines with the firmer steering to create the most confidence-inspiring overall setup. This was our preferred setting for attacking the endless series of switchbacks on our test route. Sport-plus also loosens the reins of the otherwise overactive stability control (and illuminates its warning light on the dash), allowing a welcome bit of rear slip angle. But it would take real determination, and the stability control switched off completely, to unstick the rear end. Even in sport-plus, the chassis has so much grip - on its wide Bridgestone Potenzas - that the Z4 proves endlessly forgiving, never twitchy.