I've occasionally given someone a ride for a short distance in town. Pretty rare though, and pretty contingent upon me assessing the person as harmless. Not a habit. No long distance hitchhikers. I don't stop to help people fix cars either. Even if I have the skills, I'm not AAA, and it can be just as dangerous for you. I spend a lot of time, money, and skill making sure my car is maintained and I think people can do similarly or pay for their mistakes. Consequences can focus people, and if that can't, well they're a knucklehead and I can't make them not be.
I would help someone out in a very isolated area like a National Forest, as I've been on the other side of the coin for that, plus I just think people who have made it all the way into NFs are generally more trustworthy. Sort of a "country" thing I guess.
I generally don't bite on "gas can" stories either. I'm not a bank, in fact I'm homeless with low funds. I know that some people tour the entire country telling sob stories about how they "ran out of gas." Yeah, because you decided it would be fun to tour the country on everyone else's gas money. It's called "gas canning." Learned about that in Savannah last winter. Also had some guy give me the greatest late night gas can sales pitch ever. He was either truly stressed beyond reason, or the greatest of ham actors. I don't care; I offered him reasonable forms of assistance, such as escorting him on foot to a place where he could withdraw the cash he said he could eventually get. I'm a martial artist and it wasn't an ungenerous offer, I was prepared to load up with the bear spray and the 1 foot knife in case of trouble, not that I thought it so likely. And the dog. But he didn't take me up on it, just wanted money. After going around in a circle about that for a bit, I said, "You need... to find someone ELSE... to get the MONEY." Then he finally quit and dejected he walked off.
Really, I would have helped him in tangible ways like pushing cars or adding to safety while walking, but money wasn't something I was going to give him. I do a LOT of inconveniences in my life just to save a dollar or two, to stretch that much farther, as I don't know when I'll see money again. Then someone just wants to use me like a convenience store with free stuff? No, it doesn't work that way. I give what I have to give, no more.