I have recently bought a Kia for 1,000 TC. I have tried to upload a sound clip to the Kia for use in game, but it tells me that it is not packaged in a RIFF container. I have looked around the web and everyone has said that it only works with WAV files. The file I am attempting to upload is a .wav file and it is under five seconds long.

Try reconverting it.
Get a .mp3 and then convert it to .wav

That worked. Thanks for the speedy response!