Speech-based command interfaces are becoming more and more common in cars. Applications include automatic dialog systems for hands-free phone calls as well as more advanced features such as navigation systems. However, interferences, such as speech from the codriver, can hamper a lot the performance of the speech recognition component, which is crucial for those applications. This issue can be addressed with {\em adaptive} interference cancellation techniques such as the Generalized Sidelobe Canceller~(GSC). In order to cancel the interference (codriver) while not cancelling the target (driver), adaptation must happen only when the interference is active and dominant. To that purpose, this paper proposes two efficient adaptation control methods called ``implicit'' and ``explicit''. While the ``implicit'' method is fully automatic, the ``explicit'' method relies on pre-estimation of target and interference energies. A major contribution of this paper is a direct, robust method for such pre-estimation, directly derived from sector-based detection and localization techniques. Experiments on real in-car data validate both adaptation methods, including a case with 100 km/h background road noise.