Onto a single CD that would mean that each song was only using up about 800k of data space, which in turn means the audio quality if going to be poor. However if you want to try this you need to burn a cd as an MP3 cd or MP3 Jukebox CD depending on the software you have. You'll also probably have to "transcode" your songs, ie fed them through a program that produces versions at the lower quality/bit-rate (to get 1000 you are looking at 96k bits per second, maybe a little higher).
Oh and by the way, this requires that your car cd player will read the discs! I'd try with a disc containing only a few tracks first and then then try a full disc later.