The planet, not the cars.
The Cassini-Huygens site has a collection of various recordings from both the Cassini and Huygens probes gathered during the exploration of the Saturnian system.
To play the sounds and for more information about them, click on the links below.
Sounds of Enceladus (QuickTime 678 KB)
Radar Echoes from Titan's Surface (Wav file 400 KB)
Speeding Through Titan's Haze (Wav file 400 KB)
Bizarre Sounds of Saturn's Radio Emission (Wav file 127 KB -- 13 seconds)
Eerie sounds of Saturn's Radio emissions (Wav file 718 KB -- 73 seconds)