I think the big sell from Rare is that the vehicles are meant to replace the moves-and-transformations concept from the earlier games. For example, rather than having a challenge where you'd use Kazooie's spring-jump, you'd have to build or select a vehicle that could vault up to a certain height. Instead of turning into a bee, you use a helicopter, etc. I'm sorta getting into the idea, actually.
Here are a couple of tracks that I had intended to use in an aborted Mario-themed solo concept album.
"Supar Peggio Bros" (simple piano arrangement of Super Mario Bros.)
"Whistlin' Mix" (Jazzy lounge mix of Super Mario Bros. 2, a.k.a. the take where I couldn't stop laughing)
Hm. I'm not sure if it's wise to use an 808-style beat all the way through the track. Maybe try alternating with a more realistic drumkit sound? Also there's a clashing/off-tempo hihat somewhere around 2:45. I hope these comments help.
Yeah, that's actually a medley of about seven different tracks from the Banjo series.
Specifically "Click Clock Wood", "Freezeezy Peak", "Mad Monster Mansion", "Gobi's Valley", "Cloud Cuckooland", "Mayahem Temple" and "Rusty Bucket Bay".