I Feel Like My Fiance is Being Taken Advantage Of. What Do I Do?

My fiance (who is 21) has a friend at work (who is about 40). His ex-wife took his car about 3 months ago and so now, my fiance gives him a ride to work and a ride home everyday. I was not opposed to this at first, because I understood that he wanted to help his friend. So when we got a used car- we sold him our old one for dirt cheap. But it has been months and his friend has not taken much initiative to get his out of state license changed and, now all of the sudden he needs new glasses to pass the eye exam, and so he can't afford to do some things because of other things pretty much.
My real problem is that this guy isn't even on my fiance's way to work. We live about ten minutes away from his work, but now he has to leave one hour earlier and gets home an hour later. He does alot of driving, and because of that, he is always tired. He even gives him rides to other places during the day when he should be resting after working all night long. We have a 2 month old baby girl who I don't get alot of help taking care of because he is always tired and/or sleeping. Plus, our car has been having problems and has completely bald tires it really isn't dependable in this winter weather. Last week, he hit a snowbank because he fell asleep at the wheel after dropping this guy off at home.
I am always worried about him when I know he is driving and I believe our family is being negatively effected by the inconvenience that this man has placed on my fiance.
Like I said, I understood that he wanted to help his friend, but it has been going on for too long, in my opinion. His friend has had plenty of time to get his things together and hasn't. He is causign alot of wear and tear to our vehicle and I think it is about time that this stopped before my fiance does worse than hitting a snowbank.
I have tried to talk to him, but all he sees is that he is helping out a friend. How do I make him see that he is being taken advantage of and is sacrificing to much to help someone who isn't helping themselves?