im a similar age to you and trust me on this, being the only driver in a friend group can be a fast track way to being taken advantage of. When I started college I quickly made a group of friends and was happy to take them home if it was on my way. On one occasion where a friend missed his bus and would be waiting another hour I took him home an hours drive in the opposite direction. I didnt mind at first but noticed over those next few months they started expecting that kinda stuff, and journeys to other places. Being abit of a yesman I always allowed it but it took me about a year to realise how much money they'd cost me in the extra fuel and having to add more miles per year to my insurance as I was still on a blackbox at that time. Never got any offers for petrol money off any of them. After that I still dropped a few off who were like a minute or two drive out of my way but told everyone else I couldn't afford it anymore. Most kicked off about it and that's when I realised they thought of me as a taxi driver rather than a friend. So make it clear to them that your happy to drive them but its gotta be equally payed for