I find it strange the majority of people here wouldnt ask him for money.
Its not giving a lift. Its carpooling
Every one I know who has been the person in need of being brought to work by carpooling has contributed something to the driver, be it weekly or monthly.
Granted this is probably laid out at the start.
Tell him you need the money and if he doesnt chip in he's gonna have to find alternative arrangements.
You are both adults after all..just stopping picking him up is a bit childish.talk to him properly