Disclosed herein is a method of improving the recognition accuracy of an in-vehicle speech recognition system. The method of the present invention selectively adapts the system's speech engine to a speaker's voice characteristics using an N-best matching technique. In this method, the speech recognition system receives and processes a spoken utterance relating to a car command and having particular speaker-dependent speech characteristics so as to select a set of N-best voice commands matching the spoken utterance. Upon receiving a training mode input from the speaker, the system outputs the N-best command set to the speaker who selects the correct car command. The system then adapts the speech engine to recognize a spoken utterance having the received speech characteristics as the user-selected car command.