Not all resources are strictly Rt 66, but they do give a sense of being on a road trip.
ZZ Top: Gimme all your loving
Convoy (1978) - title song
Steppenwolf: Born to be Wild
Smokey and the Bandit (1977) - title song
Bruce Springsteen; Cadillac Ranch
the Cannonball Run (1981) - title song (initial chase on I40, New Mexico)
- Fine Dining v Diners (Stan Lee)