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BMW Z3 - The //M Roadster and //M Coupe
Background
The Z3 was in the unusual position of spanning both the E36 and E46 generations of three series. This lead to the car using the S50 / S52 E36 engines and the S54 from the later model. US cars only had the single throttle body until the launch of the S54 gave our colonial cousins their first taste of the full blooded engine.
A friend with a UK //M Roadster described is as a four wheeled super bike, the most exhilarating thing he'd ever driven. Part of the reason for this isn't just the sheer performance but how low and open the car feels. They really are a unique motoring experience.
//M Roadster showing unique front bumper, mirrors and lower stance.
Mecahnicals
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Six cylinder 24 valve 3.2 |
Early //M Roadsters had the 3.2 S50B32 from the E36 //M3 Evo. In the Evo it made 321bhp but the Z was a handful of horses down due to the different exhaust. That exhaust had four tips (a first for an //M car) and as a result the rear boot floor is totally different with the battery in the middle. There's no room for a spare wheel so BMW invented the //M-Mobility system, basically a can of tyre weld.
All variants used the ZF S5D gearbox rather than the six speed from the M3. BMW claimed the larger unit wouldn't fit although aftermarket conversions have managed to squeeze it in. A limited slip differential was standard in 3.15:1 or 3.23:1 depending on model.
Two piece floating rotors to help with the thermal load.
315x28mm front discs from the Evo were fitted at the front, the rear used 312x20s. Euro cars had floating rotors in which the disc and brake hub were separate to allow for thermal expansion without warping. BMW North America declined to fit these for liability reasons in case they were poorly maintained (most states don't have an annual MoT!). Surprisingly these weren't four pot calipers, but nor were they on the E36.
When the E36 M3 gave way to the E46 M3 the Z3 was upgraded to the more powerful S54 engine. This was fairly similar to the S50B32 but gave an extra 20bhp 500rpm higher in the rev range at 7900. On the face of it then there was little difference, but the S54 redesigned and improved a huge number of parts making it a very desirable revision.
My friend's car showing the deep 17" alloys and //M gill.
The car wore distinctive staggered 17" alloys, tyres were 225/45/17 front and 245/40/17 rear. Early cars had silver, almost chrome wheel finish but this was darker on S54 models. There was a distinctive front bumper, elliptical mirrors and the side gills were a new //M version.
There were numerous detail changes, especially to the suspension which had a wider track and strengthened rear trailing arms. The car was just over an inch lower than a normal Z3. S54 cars had the spring and anti-roll bar rates upped even further.
The full blooded six throttle body S50B32 engine.
US Versions
BMW NA had decided early on that the full blooded S50 would be too expensive and liable to sitting around unloved on dealers floors. With hindsight they couldn't have been more wrong but in any event their decision gave us the US 3.0 and 3.2 single throttle body engines, similar in practice to the Alpina engines. Viewed from that perspective they seem less like second best and more like a highly tuned M50. I've been in a US E36 M3 and the engine is lovely.
So it was to be this S52 that began production in October 98 for the US market. It had the same brakes and other major features of the euro model.
When the E36 ended so did production of it's S52 engine leaving BMW little choice but to use the full fat high caffeine S54 and release the beast on the US market. The rarity and performance difference compared to the earlier model make these cars hugely expensive today.
Early US cars had ASC+T traction control, S54 models had a DSC stability control system based on the E46.
Hand stitched leather, more chrome and a few extra gauges.
Interior
The //M models came with flamboyantly designed sports seats that were quite a departure from anything else that had graced a BMW. Along with the rest of the interior they were trimmed in two tone leather using fairly bright colours such and blue and red. This extended to the dashboard which was trimmed in a style evoking the 635CSi Highline.
The centre console gained a multitude of new round dials and extra leather. Heated seats and an electric roof were standard as was aircon, technically these were options but I've never seen a car without them. The interior mirror was elliptical and the sill covers had the obligatory //M logos.
An //M Coupe on the type of road it was designed for.