The Z4's design addresses many criticisms of the preceding Z3; the Z4 is larger, and has a significantly stiffer chassis. The Z4 features a strut type front suspension like its predecessor. The rear suspension, however is considerably different from that of the Z3, which was based on that of the E30 BMW 3 Series. Instead of a semi-trailing arm suspension, the Z4 uses a more advanced multi-link suspension. It was built in Spartanburg, South Carolina. Initially, the Z4 was available only as a roadster, but in 2006 a coupé version was officially launched. The last of the first-generation Z4 to be assembled in North America rolled off the assembly line on 27 August 2008.
The Z4 offers a choice of four straight-six engines: 2.2L, 2.5L, 3.0L, and 3.2L. All are variants of the BMW M54 engine. In the European market, a 2.0L straight-4 is also offered.
The 2.2L, 125kW (170PS; 168hp) version can reach 100km/h (62mph) in 7.7s. The 2.5L engine produces 141kW (192PS; 189hp) at 6000rpm. BMW claims a 6.8s time to 100km/h (62mph) with a manual transmission. It weighs 1335kg (2,932lb) with a manual transmission — 30 kg (66lb) lighter than the 3.0L version, but still heavier than the 2.5L Z3's weight of 1315 kg (2899lb). The 3.0L, 170kW (231PS; 228hp) (at 5900rpm) straight six has a claimed time to 100km/h (62mph]]) of 5.9s.
The most powerful car of the Z4 line-up is the Z4 M. It features a naturally aspirated, in-line six cylinder engine, used in the third generation of the BMW M3, producing 252kW (343PS; 338hp) at 7,900 rpm and 365N·m (269lb·ft) of torque at 4,900 rpm. 0-100 km/h takes 5.0 seconds, and the top speed is limited to 250km/h (155mph).
Five-speed manual gearboxes are standard on all models except the 3.0L and the M Roadster, which get a 6-speed Getrag. 5-speed or 6-speed automatic are available on all non M cars. The M Roadster shares its 6-speed Getrag 217 manual gearbox with the M3.
A Sport package, adding stiffer and lower suspension, larger wheels with run-flat tires, and Dynamic Driving control, BMW's Vehicle Stability Control system, is also available.