On this page you can calculate the number of songs on a car USB flashdrive.
After treating the flashdrive with BluMeUSB this is what will fit on your flashdrive and they will load quicker !
BlueMeUSB will remove all unneccesary files like artwork or song lyrics.
A bit rate of 128 kbps is perfectly acceptable for use in your car.
Use this calculator to find out what the capacity of your USBdrive is: