I suspect the car’s stereo only accepts FAT32 format devices and the drive when new was formated as exFAT. When you reformated it you probably chose NTFS.
There are two options, 1. write to the car manufacturer and ask if they have an update to their system that will allow it to read exFAT drives. 2. By smaller drives. 32 GB and below are formated as FAT32.
Supposedly there is a 3rd option. There exists an HP format utility that will support formatting the 64GB drive as FAT32. If you can find it it may solve your problem. Use at your own risk. .
