wiki'ed the specs
seems good
[highlight]
The Z4 offers a choice of four straight-six motors: A 2.2 L, a 2.5 L, a 3.0 L, and a 3.2 L. All are variants of the BMW M54 engine. In the European market, a 2.0 L straight-4 is also offered.
The 2.2 L, 120 kW (170 bhp) version can reach 100 km/h in 7.7 s, but is not sold in the United States.
The 2.5 L engine produces 141 kW (192 bhp) at 6000 rpm. BMW claims a 6.8 s time to 100 km/h (62 mph) with a manual transmission. It weighs 1,335 kg (2,932 lb) with a manual transmission—30 kg (66 lb) lighter than the 3.0 L version, but still heavier than the 2.5 L Z3's weight of 1315 kg (2899 lb).
The 3.0 L, 170 kW (231 bhp) (at 5900 rpm) straight six has a claimed time to 100 km/h (62 mph) of 5.9 s.
The 3.2 L motor produces 246 kW (330 bhp) at 7900 rpm and (262 lb-ft) of torque at (4900 rpm) [/highlight] claimed time of 5.0s and 80% of torque available from 2000rpm
http://en.wikipedia.org/wiki/BMW_Z4