Check out APRS[0]. Solves most of the above already by centralizing data-collection. Would just need a beacon on every vehicle. No need for internet connectivity. Receiving stations can be scaled up as required. Logging of course not an issue as can be logged on-board and/or externally.

The on-board display can overlay a map and call the next stop based on proximity. Not a weekend project, I'll admit, but many existing moving parts available off the shelf.

Hams play with this stuff... a lot.

[0] https://en.wikipedia.org/wiki/Automatic_Packet_Reporting_Sys...