The Z4 replaced the Z3 in 2002 as a larger and stiffer two-seater built at Greer in South Carolina. It swapped the old semi-trailing rear axle for a multi-link layout and introduced electric power steering to a BMW. A coupé joined in 2006, and the Z4 M used the S54 engine from the M3.
BMW Z4 (E85) at a glance
| Maker | BMW US Manufacturing, Greer, South Carolina |
|---|---|
| Production | 2002–2008 |
| Body styles | roadster (E85), coupé (E86) from 2006 |
| Designers | Anders Warming (roadster), Tomasz Sycha (coupé) |
| Premiered | Paris Motor Show 2002; European sales from March 2003 |
| Rear suspension | multi-link instead of the Z3’s semi-trailing arms |
| Weight saving | aluminium bonnet and suspension parts, magnesium roof frame |
| Drag coefficient | 0.35 or better |
| Coupe rigidity | 32,000 N·m per degree, against 14,500 for the roadster |
| Z4 M engine | S54 straight-six, 343 hp outside North America |
| Total production | 197,950 cars, of which 17,094 coupés |
| Successor | Z4 (E89), from 2009 |
The range was also sold in North America with slightly lower power ratings; figures here are European unless stated.
History of the BMW Z4 (E85)
Development and launch
The E85 was designed by the Danish designer Anders Warming between mid-1998 and the summer of 1999, and its design was frozen on 1 March 2000. The car was presented at the Paris Motor Show in 2002; North American sales began in November that year as a 2003 model and European sales followed in March 2003. It started at 29,900 euros in Germany. Because it was larger and more comfortable than the Z3, it took the next number in the Z Series. Sales were strong at first but fell noticeably from 2004, which pushed BMW towards a thorough revision and a coupé version.
Chassis
The Z4 kept the MacPherson strut front suspension of the Z3 but replaced the rear semi-trailing arms with a multi-link design. Aluminium was used for the bonnet and suspension parts and magnesium for the roof frame to offset the extra weight, and run-flat tyres removed the need for a spare wheel, freeing boot space. Electric power steering replaced the hydraulic system of the Z3, with assistance that varied with speed; the Z4 M kept hydraulic steering and was judged to feel more direct. Six-cylinder engines were all-alloy units with double VANOS and an electronic throttle, and safety equipment included four-wheel disc brakes and stability control with ABS and traction control. An optional Sport Package added lower, stiffer suspension, 18-inch wheels and the Dynamic Driving Control settings for steering, throttle and gearbox.
Facelift, coupé and M versions
The revised Z4 appeared in spring 2006 with new bumpers, headlights, LED tail-lights, wheels and colours, chrome interior details, electronic oil level monitoring and hill start assistance. The M54 engines gave way to the N52: the 2.5i went from 141 kW (192 PS) to 130 kW (177 PS), the new 2.5si made 160 kW (218 PS) and the 3.0si 195 kW (265 PS); the 2.0i four-cylinder of 110 kW (150 PS) stayed. Every manual model moved to six speeds. The coupé was shown as a concept at the 2005 Frankfurt show, approved in the summer of 2004 and frozen that December; the production car appeared at the New York Auto Show in April 2006 and went on sale in late May. Its double-bubble roof gave more headroom and its fastback rear window ended in a spoiler shaped for downforce. The Z4 M arrived in 2006 with the S54 engine, 343 hp in most markets and 330 hp in North America, a wider front track, revised suspension and a quicker steering rack; it reached 100 km/h in 5.0 seconds and was limited to 250 km/h, with 275 km/h available as an option. Nine works racing Z4 M Coupés with a 420 PS engine ran in the VLN series. Production ended in August 2008 after 197,950 cars.
Design and features
- Multi-link rear axle: a more sophisticated layout than the Z3’s semi-trailing arms.
- Electric power steering: the first BMW with electric rather than hydraulic assistance, speed-sensitive in operation.
- Lightweight parts: aluminium bonnet and suspension, magnesium roof frame and run-flat tyres without a spare.
- Coupé rigidity: 32,000 N·m per degree of body twist, more than twice the roadster’s figure.
- Z4 M: S54 engine, hydraulic steering and the quicker rack of the M3 CS and CSL on the coupé.
BMW Z4 (E85) versions
- 2.5i and 3.0i roadsters: the launch models of 2002.
- 2.0i: four-cylinder model sold in Europe from May 2005.
- 2.5i, 2.5si and 3.0si: N52-engined models after the 2006 facelift.
- 3.0si Coupé: the only non-M coupé, with a six-speed manual or automatic.
- Z4 M Roadster and M Coupé: S54 engine, 343 hp, hydraulic steering.
- Z4 M Coupé works racer: nine cars with a 420 PS engine for the VLN series.
The Z4 replaced the Z3 and used engines from the 3 Series (E46) and later the E90. The retro-styled Z8 was the flagship of the same years, and more cars are in the BMW collection.
Sources
- BMW Z4 (E85), English Wikipedia: development, body styles, chassis, equipment, Z4 M
- BMW E85, German Wikipedia: facelift, engines, production totals, racing
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