It’s tough, but @CyanoticWasp is right when he says you should address it head on, though I can’t agree with the statement that he should be embarrassed, or that he shouldn’t even ask about petrol money. What would you do if you wanted to see him, but couldn’t afford to, and knew he could pay for it?
Are you resenting it because it’s becoming a financial strain or because you automatically assume that he’s only into you for your money?
Perhaps he has some financial issues that he’s embarrassed to talk about, and though he likes you for you, he is finding it hard to continue spending the little he has to make the trip. You say that he rarely pays, suggesting that he does on occasion. Maybe what he has spent so far has been more than he could afford, but has kept quiet because he didn’t want to appear as poor as he is. Perhaps he could pay for meals, but is feeling less than wealthy and it seems to him like you don’t mind paying for things, so he doesn’t bring it up. People can act funnily in new relationships sometimes, and maybe he’s just put up the image that he’s financially stable because he thinks that that is what you need him to be.
@worriedguy has a great point about what people would think if the genders were reversed. We’re well into the 21st century, after all.
No one here can tell you for certain whether or not this fellow is trying to take advantage of you, or if he genuinely enjoys seeing you but can’t afford it. The best thing to do is address it head on. Figure out what you need a partner’s financial contributions to be, and ask about his ability to meet that need. If he’s genuinely dirt poor, are you okay with that? Can you make an arrangement that works for both of you? If the relationship were to progress further, would you be happy as the primary breadwinner? Whatever the arrangement, there is no right or wrong way to handle it, as long as you’re both being clear and honest about it, and can be happy.
Ask him directly, be open minded, and use your judgement. Good luck!