While the Toyota GR Supra is rumored to get a hardcore, more powerful GRMN variant, BMW currently has no plans to give the BMW Z4 the full-fat M treatment. Roadster sports cars are considered niche, so BMW simply can't make a business case for a high-performance Z4.
That means the most powerful version of the BMW Z4 is the M40i, which packs a 3.0-liter turbocharged inline-six producing 382 horsepower and 369 lb-ft of torque, which is sent to the rear wheels through an eight-speed automatic.
This setup enables the roadster to sprint from 0-62 mph in just 3.9 seconds. In Europe, however, the M40i only has 335 hp due to stricter emissions regulations. To rectify this, German tuner Lightweight Performance has given the European Z4 M40i a power bump. The same tuner also recently added more power and less weight to the BMW M2 Competition, effectively making it the next best thing to an M2 CSL.
By tweaking the ECU, Lightweight Performance has increased the Z4's 3.0-liter turbocharged inline-six to 395 hp and 420 lb-ft of torque. That's 60 more hp than Europe's Z4 and 13 more hp than the US version. It also packs nearly as much power as the M2 Competition. No 0-62 mph time has been quoted, but it should be slightly quicker off the line than the stock Z4. Top speed has increased to 186 mph, however, by removing the speed limiter.
To make the Z4 look more like a proper M car, Lightweight Performance will also install a new quad exhaust system finished in either black or carbon fiber. A new downpipe also enhances the car's soundtrack, or the tuner also offers a stainless steel silencer. Aero enhancements include a carbon front splitter and lip spoiler to increase downforce and high-speed stability, and the tuner is also developing a carbon fiber rear diffuser.
Lowering springs reduce the ride height by 0.5 inches an adjustable Bilstein suspension system will also be available later this year. A staggered set of 21- and 20-inch wheels wrapped in Michelin Pilot Sport 4 S tires complete the look. No pricing has been announced, but the standard BMW Z4 M40i starts at $63,700.