Does Apple car play use data
iPhone 11
iPad (10th generation)
Question marked as
Apple Car Play is just an extension of your iPhone. So any activity involving data transfer from the Internet (maps, online music, text messages, etc..) will use the same amount of data whether you see it on your phone or on Car Play.
Between the phone and Car Play it's local communication (Bluetooth or cable), so if you play music stored on the phone it's free.