AS far as lithe, powerful sports cars go, BMW's original Z3 M Roadster was hard to beat. But that didn't stop some criticising its twitchy handling, primitive Z-axle rear suspension and the fact its ballistic M3-sourced 236kW straight six could easily overpower its Z3-based chassis. Fast forward almost five years and the lack of an M version of the Z3-replacing Z4 has been rectified. No longer nobbled by a five-speed manual transmission, complete with the E46 M3's 252kW six and having shed the uncommunicative electric steering of lesser Z4 variants, the new M Roadster is stiffer, quicker and more refined than ever. Approaching the pace of its M5 stablemate, it's more complete than its predecessor - without losing any of its animal instinct.