This takes me back a few (!) years, but my most memorable experience driving to music was with "Equinox" from the "Coltrane's Sound" album. This was not pushing the speed limit, but settling back in the groove music... very "groovy"!
Best driving music.
I'm not a car audio buff, nor am I a huge traveler, but in the northeast we've had beautiful weather the last couple days and I've been REALLY enjoying The Allman Brothers. Man, the fresh air blowing though the car and Blue Sky cranking on the radio, does it get any better than this? What do you like to listen to on a great Saturday, just cruising with the top down?