Z4 M Coupé
The coupé model was introduced to the public first in concept form at the 2005 Frankfurt Motor Show and then in production form at the 2006 Geneva International Motor Show[11] with production starting shortly after.
The Z4 M Coupé has a fastback hatch design, resulting in a different body shape to its Z3 M Coupé predecessor. The roof and windows add an additional weight of 10–15 kg as compared to the roadster. BMW North America press kits report the Coupé's weight as 1465 kg[12] while other official BMW materials show a weight of 1495 kg.[13]
The official 0–97 kph acceleration time is 5 seconds and the top speed is electronically limited to 155.5 mph. The Z4 M Coupé set a laptime at the Nürburgring Nordschleife of 8 minutes and 15 seconds.[14]
Z4 M Roadster
The roadster model was launched in late 2006.
Weighing 1450 kg,[15] the M Roadster has a 0-60 mph time of 4.7 seconds and a top speed electronically limited to 250 km/h. Unlike the Z3 M Roadster, the external dimensions of the Z4 M Roadster are the same as the standard Z4.
Engine
The M Coupe and M Roadster are powered by the BMW S54 straight-six engine from the E46 M3. The engine has fly-by-wire throttle and double VANOS (variable valve timing).[16] In most countries, the engine is rated at 252 kW at 7,900 rpm and 365 Nm at 4,900 rpm- the same outputs as in the M3. The engine has a redline of 8,000 rpm. Cars sold in North America produce 330 bhp at 7,900 rpm and 262 lbft of torque at 4,900 rpm.[17][18] Unlike the S54 engine from the E46 M3 and Z3 M Roadster and Coupes, where BMW used the same MSS54 DME, the Z4 M Coupe and Roadster engine is controlled by the MSS70 DME[19] which makes popular ECU tuning options for S54 engines on the E46 M3 and Z3 M models obsolete on the Z4 M.
Drivetrain
The engine was exclusively mated to a 6-speed "Type H" ZF manual transmission since the M3's Getrag 420G 6-speed transmission did not fit the Z4's chassis. This version of the ZF S6-37 transmission is designated ZF GS6-37BZ-TJEE and is similar to the one found in the 3.0i and 3.0si.
The Z4 uses the same limited-slip differential as the E46 M3. This clutch-type, torque-sensing LSD features the Variable M Differential Lock, codeveloped with specialists at GKN Viscodrive GmbH.[20]
Chassis
The suspension system consisted of a strut design at the front and a multi-link design at the rear. The M Coupé's springs have higher rates and the dampers are more aggressive compared to the Z4 M roadster. The car achieved a lateral acceleration of 0.89g on the skid pad.[17]
The Z4 M uses hydraulic power steering, unlike the electric power steering used by the rest of the Z4 range, and has thick rimmed steering wheel.[17] Other changes include a wider front track, revised front suspension and steering geometry.[18] All Z4M models feature a quicker steering ratio than the E46 M3 or E46 M3 CSL, with the M Coupé having an even quicker rack than the M Roadster.
Many components were shared with the E46 M3 including the rear subframe, rear anti-roll-bar mounting points, wheel bearings, and original equipment Continental ContiSport Contact tires.[21] Front lower control arms are shared with the E46 Performance Package (ZHP)
Brakes
The braking system shares many parts in common with the E46 M3. The brake calipers are from the M3 Competition model and the brake discs (consisting of aluminum hubs, stainless steel pins, cross drilled iron floating rotors) are from the E46 M3 CSL. Despite increases in rotor size, brake pads are the same part number for all E36 M3, E46 M3, and M Roadster/Coupé models.
Production
Production began on 4 April 2006 and ended in 2008 when the E85/E86 Z4 was replaced by the E89 Z4. A total of 4,275 M Coupes were produced, and 5,070 M Roadsters.[23] This included 1,815 M Coupes for North America and 3,042 M Roadsters for North America.[24]
