BMW Z4 (E85). The first generation of the BMW Z4 consists of the BMW E85 (roadster version) and BMW E86 (coupe version) sports cars. The E85/E86 generation was produced from 2002 to 2008. The E85/E86 replaced the Z3 and is the third model in the BMW Z Series. Initial models were in the roadster (E85) body style, with the coupé (E86) body style being added in 2006.  In February 2009, the BMW Z4 (E89) began production as the successor to the E85/E86.

As was its Z3 predecessor, the E85/E86 was manufactured in Greer, South Carolina.  The M model, the Z4 M, is powered by the S54 straight-six engine.

Development and launch 
The E85 was designed by Danish BMW-designer Anders Warming from mid-1998 to the summer of 1999. The coupe models were designed by Tomasz Sycha. The E85 designs were frozen on March 1, 2000. The Z4 was introduced at the Paris Motor Show in 2002, and North American models went on sale in November of the same year (as the 2003 model year). European sales began in March 2003.

Initial models consisted of the roadster body style powered by a 2.5L or 3.0L 6-cylinder engine.

Body styles

Roadster (E85) 
The Z4 Roadster was launched in 2002 with the 2.5i and 3.0i six-cylinder models. Transmission choices were a five-speed manual, six-speed manual, five-speed automatic and a six-speed SMG-II automated manual transmission.

A four-cylinder model, the Z4 2.0i Roadster, was introduced for the European market in May 2005.

The drag coefficient is maximum of .

Coupé (E86) 

BMW unveiled a concept coupé version of the Z4 at the 2005 Frankfurt Motor Show. The design of the Z4 and Z4 coupé has variously been ascribed to Anders Warming, Chris Bangle, the controversial former BMW Head of Design, and Adrian van Hooydonk, former BMW chief designer, and BMW designer Tomasz Sycha. The design was approved in Summer of 2004 and frozen in December 2004. The company announced in 2005 that the two-door coupé would be available for production including the return of the M Coupé. The production car was introduced at the New York Auto Show in April 2006 and was available for sale in late May 2006.

Thanks to its hatch design, the Z4 Coupé offers  of trunk space, compared with  for the roadster.

The Coupe's fixed roof increases torsional rigidity, resulting in a stiffness of  per degree of body twist on the coupe (compared to  per degree on the roadster), which improves turn-in and overall handling response. The roof has a "double-bubble" contour which serves as an aerodynamic aid and offers more headroom than the roadster with the soft top closed. The Coupé has a sleek fastback rear window that slopes down to an integrated spoiler which is shaped to deliver downforce to the rear axle at high-speed.

The model range for the Coupé was more limited than the roadster, and consisted of the six-cylinder 3.0si and Z4 M model only. Transmission choices were a 6-speed manual and a 6-speed automatic with shift paddles mounted on the steering column.

Chassis and body 

Compared with its Z3 predecessor, the Z4 is larger and has a stiffer chassis. As per the Z3, the front suspension is a Macpherson strut design. The rear suspension uses a multi-link design, instead of the semi-trailing design used by the Z3. 

The Z4 used lightweight materials to offset the increased weight over the smaller Z3, such as an aluminum hood and suspension components, magnesium roof frame. Run-flat tires removed the need for a spare tire, which reduces weight and allows for a larger trunk.

Equipment 
The 6-cylinder engines included all-alloy construction, variable valve timing (double-VANOS), and throttle by wire. Safety technology included four-wheel disc brakes and electronic stability control, incorporating ABS and traction control.

An optional "Sport Package" included added stiffer and lower suspension, 18 inch wheels, and sport tuned electronic steering, throttle and shift parameters ("Dynamic Driving Control").

Electric power steering replaced the traditional hydraulic power steering used by the Z3. The power assist is speed-sensitive, allowing for easier maneuvering at low speeds.  However, the Z4 M uses hydraulic power steering, and has been judged as having a more direct and communicative feel to the steering.

In 2002 a 6-speed SMG gearbox was offered as an option on the 2.5 and 3.0 roadsters.

Transmissions 
The available transmissions were:
 5-speed manual Getrag S5D250G (2.2i, 2.5i)
 6-speed manual Getrag GS6-17BG (2.0i)
 6-speed manual ZF GS6-37BZ-TJEE (Z4M)
 6-speed manual ZF GS6-37BZ-THEA/TJES (3.0&3.0si)
 5-speed automatic ZF 5HP19 (2.2i, 2.5i, 3.0i ~ MY 03-05)
 6-speed automatic ZF 6HP19 (2.5si, 3.0i, 3.0si ~ MY 06-08)
 6-speed GS6-S37BZ SMG automated manual (2.5i, 3.0i)

Models 

* The 2.0i was only sold in Europe.

All models are E85 roadsters except as noted. European specifications shown. North American vehicles may have slightly lower power ratings. US models include 2.5i Roadster, 3.0i Roadster, 3.0si Roadster & Coupé, M Roadster & Coupé.

Z4 M versions 

The Z4 M Coupé/Roadster was introduced in 2006 and is powered by the S54 straight-six engine shared with the E46 M3. The S54 was also on the Ward's 10 Best Engines list for 2001 through 2004. The engine in the North American Z4 M models are rated at  at 7,900 rpm, 3 hp less than the North American M3. In other markets, the power output is the same  as the M3. The engine had BMW double VANOS system and a compression ratio of 11.5:1. The torque generated by the engine amounted to  at 4,500 rpm. The torque was available from 2,500 rpm.

The Z4 M uses hydraulic power steering, unlike the electric power steering used by the rest of the Z4 range. The Roadster used the E46 M3 steering rack, the Coupé the faster M3 CS/CSL rack. Other changes include a wider front track, revised front suspension, wider non-runflat-tires (measuring 225/45 at the front, 255/40 at the rear), and steering geometry. The brakes and the entire rear axle was too from the M3 CS/CSL.

The M Coupé's production began at the Spartanburg BMW plant in Greer on 4 April 2006.

Special models

Alpina Roadster S (2004–2006) 

The Alpina Roadster S is a high-performance iteration of the pre-facelift Z4 introduced at the 2003 Frankfurt Motor Show. Manufactured by German automobile manufacturer Alpina, the Roadster S was assembled at the manufacturer's Buchloe plant from body-in-white sent by the Spartanburg BMW factory. The Roadster S was produced for two years (2004 to 2005) before production was halted due to stricter emission regulations stopping engine supplies. The Roadster S was available in two trims, those being Standard and Luxury with the Luxury trim adding more creature comforts and bigger wheels over the Standard trim. The car had a claimed top speed of  and accelerated to  from a standstill in 5.3 seconds. The engine was modified by Alpina and change the name to E5/2. The engine create max output 300hp and max torque 362 Nm.

Concept Coupé Mille Miglia (2006) 

The Concept Coupé Mille Miglia is a concept car inspired by the BMW 328 Mille Miglia Touring Coupé. It was unveiled at the 2006 Mille Miglia rally in Italy.

Using the Z4 M Coupé's mechanical components, the concept car is  longer,  wider but  flatter than the Z4 M Coupé. Other features of the concept car include 20-inch alloy wheels with 245/40R20 tyres, permanently integrated sidewalls, swing-up cockpit, an LED headlight panel, silver-coloured carbon-fibre reinforced plastic body and an interior constructed from stainless steel, untreated cowhides and Lycra fabric.

The vehicle was designed by Anders Warming.

Model year changes

2005 
 Four-cylinder model (2.0i) introduced.

2006 facelift or LCI 

The Z4 facelift (also known as LCI) models were launched at the 2006 North American International Auto Show in Detroit. The major changes were:
 Introduction of Coupé models.
 Introduction of the M Roadster, powered by the S54 straight-six engine (the M Coupe began production a few months later, in April 2006)
 Discontinuation of the 2.2i model.
 Introduction of "si" models.
 Six-cylinder engines (aside from the M Roadster) upgraded from the M54 to the N52.
 Revised headlights, front bumper and tail lights.
 Availability of the six-speed automatic transmission.
 Inclusion of the six-speed manual transmission as standard equipment on all models.

Production 
Over the Z4's life cycle, 197,950 vehicles had been produced, with 180,856 roadsters and 17,094 coupés.

The last of the first-generation Z4 (Z4 3.0si Roadster in Space Grey) rolled off the production line on 28 August 2008.

Roadsters 
The Z4M Roadster had a total worldwide production of 5,070, including 3,042 cars for the North American market.

Coupes 
The worldwide model breakdown for the E86 Coupe over its life cycle (2006–2008) is 12,819 Z4 3.0si coupés, and 4,275 Z4M coupés. Even from its introduction in 2006, the Coupé was relatively rare: In its first 13 months on the market, the roadster outsold it at a ratio of 7 to 1. For the UK 3.0si coupe model, 1598 cars were produced with a manual transmission and 1998 cars with an automatic transmission.

The North American (United States and Canada) production total for coupe models is 3,919, comprising 1,815 M-Coupes and 2,104 were the 3.0si Coupes. Of the 2,104 3.0si Coupes produced for the North American market, 1,276 were automatics and 828 were manual transmission; the Z4M was only available with a manual transmission.

In North America, the 3.0si coupe was only available for sale in the United States although a number were imported into Canada from the US.

The yearly breakdown of North American market coupe production totals are as follows:

Motorsport

Endurance racing 

Dieter Quester, Dirk Werner, Jamie Campell-Walter and Tim Mullen won the Silverstone Britcar 24-Hour race with a BMW Z4 M Coupé. The unit of the racing version is a modified version of the S54B32 3.2-litre straight-six engine, producing approximately . The car is made by BMW's M Division and called the Z4 M Coupé Motorsport.

In the 2008 Super Taikyu Endurance Series in Japan, the Petronas Syntium Team entered two Z4M cars. The cars dominated the series by taking first and second at every race, finishing the Super Taikyu 1 class in first and second place to win both the championship and drivers title. The Petronas Syntium Team earned 277 points, compared to the next placed team on 98 points. The cars were driven by established and popular drivers such as Fariqe Hairuman, Nobuteru Taniguchi, Masataka Yanagida, Manabu Orido and father and son pairing of Hans-Joachim Stuck and Johannes Stuck.

Super GT 
In August 2008, a modified Z4 debuted in Round 6 of the Super GT season, marking BMW's return to the series after the M3 was retired from the JGTC series. It was run by the Studie team and participated in the GT300 class. The car was powered by a detuned version of the S62 V8 engine from the E39 M5. The Z4 competed in the 2009 Super GT season (aside from than Sepang Race), and they would replace their H-pattern to a sequential transmission, as well as their S62 Engine with an S65B40 after race 3, after they had suffered an unrepairable engine blow in race 2 at Suzuka. The car was retired at the end of the 2009 season, with its E89 Z4 GT3 successor making its debut in the 2010 season.

References

Z4
Rear-wheel-drive vehicles
Roadsters
Coupés
Cars introduced in 2002
Cars discontinued in 2008