2010 bmw z4 roadster 013
bmw z4 sdrive35i 02Enlarge Photo
The news, reported by the UK's iMotor, quotes an unnamed BMW spokesperson as saying, "Given the current economic crisis there is no business case for a full-on M version of the Z4." Given the weakness of the source, it's hardly a definitive statement on the matter, but the logic underlying the decision is undeniable.
As BMW's already full lineup grows, M models of certain cars are beginning to become non-starters - they'd encroach to heavily on higher-ranked vehicles, at least in terms of performance. See the 1-series for another prime example of this phenomenon.
This isn't really something you can fault BMW for, however - their standard, non-M vehicles have gotten so fast, so powerful, that simply upgrading them would put them in contention with a whole other rank of vehicle. From a consumer's standpoint, that's about the best way to lose a high-performance variant.
The standard Z4, for instance, gets a conservatively-rated 300hp (224kW) twin-turbo 3.0L inline six or a 255hp (190kW) variant of the same engine, sans-turbo. Even the lesser of these two roadsters dashes to 60mph in 5.6 seconds, with the turbo car threatening to break into the high 4-second range.
Adding another 50hp (37kW) and wringing even more out of the braking, suspension and chassis would just put the car into a price and performance class alongside the M3 - something which just doesn't make sense, even in BMW's expansive and overlapping lineup.
Instead of a 'full-on' Z4 M, there could be a Z4 'M Sport', with a tweaked and tuned ECU and exhaust system, visual enhancements, and interior upgrades, however.