Should you have to pay your boyfriend gas money

So just wondering quite a few times my boyfriend had asked me to pay petrol money when i tell my friends they all say it’s wrong and that I shouldn’t be paying it. I get the train to his house which costs me £30 and then he picks me up from the train station and drives me to his house which is only a 10 minute drive away and then he drives me back to the train station and I get the train home. So for a 20 minute journey I pay £20’petrol money that would probs last his car 1-2 weeks and I only see him like twice a month as it’s long distance so I’m basically fuelling his car and I gain nothing from it. He is an engineer and has loads of money while I work for minimum wage. If he takes me somewhere that is far away or takes longer I always offer to pay petrol money but when it’s just to his house i wouldn’t mind walking the distance for free but he insists picking me up. Also we was at his friends house before and I mentioned in front of his friends that I would buy the first round of drinks as I still owed petrol money and he was like what are you talking about you dont need to pay me petrol money I would never make you pay anything like that yet he does lol but was being weird about it in front of his friends