Please help

After exporting the Audacity file as WAV, the CD will not play on my car stereo
or any other CD player outside of the computer. I am using an iMac OSX
and burning in Toast Titanium (Spin Doctor). The Audacity file is AIFF.
Is there such a thing as a universal audio format for CD’s?

Yes. “16 bit 44.1kHz uncompressed PCM WAV”.

I don’t know your CD burning software, but it must be set to record an “Audio CD”, not a “Data CD”.