FlexCar
A number of my friends use FlexCar for those odd occasions when they are going to need to haul larger objects or numbers of people. I've watched them make it work for them, and it really does.
I had doubts, but some have morphed into where they've sold their cars and rely completely upon FlexCar. They can reserve the vehicle and location online, and it's a simple process. No one has expressed anything except delight to me, although I'm sure there are problems.
I'd do it, but I don't hang out in densely populated areas, there aren't any around here.
Arf