I looked at and played Roadtrip. It belongs in the borderline category as well. It is a prequel to ChoroQ, and plays very similar with the same gameplay elements. Open world, missions, talking to other cars, storyline, in short: the same quirky, light-hearted and charming genre hybrid between racing and RPG.

Added to the borderline category:
Everywhere Road Trip.* E-game/Takara, Conspiracy Entertainment, 10/26/2002.

I read that usually Takara is credited with the development of the series, but the developers are actually outside developers cooperating with Takara. In case of Road Trip that is E-game, and for ChoroQ I changed the entry and added as a developer Tamsoft.

These two games are not hidden gems, they are by no means perfect but they are worthwhile playing because the concept and execution is just downright playful, charming and very well done!