I'd not be overly impressed at his response. He could take your car, you could drive back so he'd only do half the driving, you pay the fuel of course...
I'd expect my partner to do it, perhaps grumpily, he's not good with changes of plans but I'd expect him to understand that a lift home is a LOT nicer than dragging your arse 6 hours via two coaches to get home...
For those making out its no different, what planet are you on?
6 hours on a coach, with likely no chance to get decent sleep, plus a change... is not in ANY way comparable to being picked up, even with a wait, in relative comfort at an airport, and then being driven with company/driving your own car back with company, for a couple of hours.
OP clearly states his only work committment is 1 meeting, not a full days paying work so he's losing his spare time not paid hours.
If you begrudge a partner a few hours of your time to help them out, whats the bloody point?!