THE Boxster's aerodynamic shapes were determined as much by what you can't see as what you can. In fact, the smooth under-floor area that is an integral part of the Boxster's design contributed 6 per cent to the aerodynamics. Careful underbody shaping also reduces front-end lift by 36 per cent. Half 911 (at the front) and half exclusively Boxster, the two-seat soft-top also incorporates a retracting rear spoiler that actives at 120km/h and slides out of the way below 80km/h.