The Z4 looks sharp but is unimpressive as a sports car. Handling is capable and secure but vague steering, a penchant to understeer, and a taut, jittery ride undermine the Z4's fun factor. Its 2.0-liter, turbocharged four-cylinder is powerful and returned an impressive 28 mpg overall, but it has a diesel-like clatter at idle. The retractable hardtop keeps the cabin fairly quiet. The well-finished cabin is very snug. The six-speed manual is precise but slightly notchy; an eight-speed automatic is optional, as are powerful six-cylinder engines with a seven-speed sequential transmission.