The Z4 M is powered by the same 3.2-litre straight-six engine featured in the BMW M3(E46), detuned slightly to fit in the Z4's smaller engine bay. The engine’s performance figures are: 3,246 cc displacement, 330 bhp (246 kW) at 7,900 rpm, 262 lb·ft (355 N·m) of torque at 4,900 rpm, 8,000 rpm redline. Output per litre is 103 bhp (77 kW), and power-to-weight ratio is 9.9 lb/bhp. Acceleration to 60 mph (100 km/h) comes in 4.8 seconds and top speed is limited electronically to 155 mph (249 km/h).