When you use your car’s built-in speakerphone feature, the speakers in the car door reverberate, sending the sounds outside of the car. Maybe don’t do this while your car is parked. Everyone in the neighborhood or store parking lot can hear your very intimate or business-related conversation.
Who said anything about driving
Ah, gotcha. I was wondering why someone would be sitting in their unmoving car while having their phone connected to their car’s audio. So I figured this was while driving. But I see how I misinterpreted it now.