I don't think this Streetview driver in Portland, OR got permission to be on the unopened busway on the MAX Orange Line:
https://goo.gl/maps/cRRekUsually if a transit agency allows this, they'd have a crowd of personnel to greet the car.
I'd love to see Google Streetview coverage of busways, subways and railways eventually. Especially Seattle's, which has a few art installations in tunnels that you normally can't see as well as weird stubs and unused segments (especially when the bus tunnel converts to rail-only).