I recently was (and still kind of am) in a situation similar to yours. I hope it's not unwelcome but I feel like I need to put my story here and hopefully give you some advice as well. I'm going to apologize in advance for the wall of text.
When I flunked out of college last year I knew I was a serious fuck-up. During the month or so after coming home I hid my grades from my parents and wallowed in my own self-hate. I hit rock bottom emotionally and had pretty much consigned myself to being king of the losers. I cut all social ties and video-games became my life.
By the insistence of my parents I got a job hauling sod and doing landscaping for a golf course. It was the first legitimate paying job I had ever gotten and it was hard work. It was a hot summer and let me tell you sod is heavy as hell. I would come home sore, sunburned, and absolutely wrecked from my allergies.
One day I caught a look at myself in the mirror after getting out of the shower and saw something rarer than a unicorn. I had a fucking bicep. It wasn't anything huge but holy shit it was MY bicep. It was tan too. I was tan, had some muscle, and looked moderately good! The person I looked at in the mirror was a complete stranger. This guy did not look like a fuck-up.
My whole worldview shifted after that. I could change who I was. I didn't have to accept myself and it was possible to un-fuck my life.
The first thing I did was quit gaming. I'm not sure how I came to recognize it as an addiction, but at some point I decided to go full Cold Turkey and drop it from my life. I think I have about $1000 invested in my steam account but I don't know the password anymore so I can't check. I relapsed several times into shitty F2P Call of Duty clones but its been a while since I played any kind of video-game.
The second thing was to get my school back on track. I don't think you are in the same boat as me on this one but I approached my parents, admitted I had seriously messed up, listened to them when they gave me advice, and talked to them about my future.
I enrolled in some online courses and worked hard to get my study skills back. You would be surprised how much you can get done when your life isn't dedicated to trading for hats in old videogames. I'm still working on my study skills. Not every day is as productive as the otheres, but I have made a ton of progress using habit/goal trackers and some of the awesome tips from /r/GetStudying.
I have a few more goals I want to fulfill like daily workout routines and reconnecting with friends. It's been a long summer but I'm seriously turning my life around for the better.
My motivation for all of this was that I did not want to go back to being a fuck-up. Its not much progress but holy shit I can not go back to being that loser in his parents house playing video-games as a career. A day doesn't go by where I think of that kid and wonder what the hell he was thinking. I would love to go back in time and make him at the very LEAST go outside.
If you've read this far thank you so much. It feels good to put this down somewhere and even better for someone else to read it. Here's some specific advice for you OP.
If you want to get a car you need to pay for it. You should get a job. I know it's scary but I wish every day I could have started working and getting a paycheck earlier in my life.
You mentioned an addiction. I'm not sure what you're facing but it's obviously not doing you any favors. Drop it. It's often said as a joke that "The first step is admitting you have a problem" but you need to vocalize what is wrong and then act. Delete, trash, purge, whatever you need to do.
Talk to your parents or a peer about your problems in school. Really listen to them. It is scary as hell to talk about grades with parents/teachers (at-least in my experience) but if you approach them with a serious intent to improve they will help you and give you resources. And for the love of god do not blow them off. Act on their advice.
I'm still working on getting out of my bubble socially but I've made a few friends through work. Be nice to people and ready to listen. Some people naturally have amazing social skills and some of us have to work up to it.
One thing I want to add as my own personal tip is to keep a journal. Writing down your feelings and what you do during the day helps you to analyze your problems and help you find solutions. At the very least keep a tee chart and set your goals for the day in the morning and then at night write down what you accomplished. Though I would seriously recommend keeping a full journal/diary.
OP I hope you get yourself out of this funk. I know what it's like to hate myself but trust me when I say that it can get better. Put ALL of your effort into that first step and then work on keeping the momentum of that step. I believe in you!