“No internships (I would despise working in a corporate setting sitting behind a desk and fetching coffee) and no job.”
Well, those aren’t the only kinds of internships 
Different businesses/organizations do internships differently. I’m an intern at a local nonprofit this summer and it’s nothing like that; it’s not for an organization I plan on staying with and it doesn’t really match any of my future plans, but I’m getting the work experience and learning about what it takes to run an nonprofit. Who knows, maybe that experience will help me somehow in the future, even if not directly.
Since your mom uses the car right now while you’re home for the summer, (I’m assuming), can you get some kind of employment during the school year? Maybe on campus? And even if you think you’d despise working in an office you might want to give it a try anyway. Maybe it wouldn’t be as bad as you think, and even if for some reason it WAS awful it would only be temporary.
I mean you can’t be too picky dude at some point if you get an opportunity to be employed, even if it’s not the most ideal one out there, go for it! Getting an internship in an office doesn’t mean that’s what you’ll spend the rest of your life doing and any work experience you can get now will help you secure a job that you can use to support yourself while you figure out your next steps.
(also – I’m just an undergrad too so please take anything I say with a grain of salt. The more experienced adults here might have different stuff to say)