E85 Z4 Series II

BMW’s "most radical traditional sports car" came in for a midlife upgrade and, as usual, it was all about the engines.

Yes, there were subtle styling differences, along with new technology and more equipment, but the headline acts were two fresh 2.5 and 3.0-litre magnesium-alloy straight sixes.

The Z4 2.5si uses the same 2.5-litre six that’s found in the E90 325i sedan and E60 525i sedan, delivering 160kW of power at 6500rpm and 250Nm of torque from 2750 to 4250rpm.

Delivering 195kW and 315Nm, the 3.0si sprints from zero to 100km/h in a claimed 5.7 seconds for the six-speed manual. Both models also offer a six-speed automatic.

The facelifted Z4 also provided a tasty entrée to the born-again M Roadster.

Powered by the same legendary 3.2-litre inline six that propels the E46 M3, the Z4 M convertible delivers 252kW at a revvy 7900rpm, along with 365Nm of torque at 4900rpm.

In contrast to the regular Z4 roadster, the M’s chassis has been tweaked to handle the extra performance, the controversial electric power steering system makes way for a traditional hydraulic power-assisted rack-and-pinion system, and the run-flat tyres are deleted for regular items.

Cross-drilled M brakes, the M3’s variable M rear differential, and redesigned bumpers also make up the package.

In October 2006, BMW released the Z4 Coupe, recalling the ballistic oddball Z3 M Coupe of the late 1990s.

It features the same long-bonnet, short-overhang profile as the roadster, along with a small hatchback for (light) luggage applications.