Where is your girlfriend commuting from? If she’s somewhere in the South Hills it’ll probably be cheaper to park at a T station (parking is free at most of them) then pay the fare to ride into and out of town, but if she’s commuting from somewhere else (such as Coraopolis where your flair says you’re located) she’s best off parking in one of the garages on the North Side near the T there and then riding the rest of the way. Alternatively she could take a chance on one of the buses that passes near where she lives on the way into town and bypass both parking garages and riding the T entirely.