Cars have changed from pure transportation devices to fully interactive, voice-based systems. While voice interaction in the car has previously required on-board processing, the growing speed and ubiquity of wireless technologies now enable interaction with a distant source. Will the perceived source of the information influence driver safety, responses to the information, and attitudes toward the computer system and car? A between-participants experimental design (N = 40) of computer proximity-in-car vs. wireless-using an advanced car simulator, found that people's driving behavior, verbal responsiveness, and attitudes are affected by computer proximity. A path analysis shows two counterbalancing effects of computer proximity on driving behavior: drivers feel more engaged with the in-car system than the wireless system, which leads to safer driving behavior; however, drivers also drive faster while using the in-car system than the wireless system, which leads to more dangerous driving behavior. Consistent with greater feelings of engagement with the in-car system, people also feel less discontentment with the in-car system and self-disclose more to the in-car system. Positive perceptions of information content also lead drivers to be more persuaded by driving recommendations. Implications for the design of wireless systems are explored. (C) 2006 Elsevier Ltd. All rights reserved.