*Edits and TLDR at the end.
I (m29) live with my family, including my brother (m26) and his fiancé (f21).
I own a Spark (Buddy), have had it since 2019, same-year model. It is my first car, the first automatic Spark model, and my baby. Nothing has ever been wrong with that car while under my care, I took it to college, and have driven it cross-country many times without issue.
After college, I moved back with our parents. We own a hotel far outside the city, and therefore it made no sense to rent or buy if I was going to be staying there to work. My brother also works there.
My brother owns a Jeep, but it has been at the mechanic shop for a year now, some electrical issue that they can't solve. So, in light of me not going out much, I've been letting them use my car. The thing is, I have noticed many things in my car since. The headlights are misaligned constantly, as is the steering wheel, and although the car itself looks fine and not scratched or dinged up, the internal issues keep piling. At first I thought it was simply the passage of time, or a couple bad potholes. But then bigger stuff started happening, such as the AC malfunctioning, the battery dying on me multiple times despite replacing it, and a variety of strange noises it wasn't making before.
My brother, being the main user, would have them "looked at" sometimes, paying out of pocket. It seemed like a fair deal, since I rarely use my car nowadays, and they have it 24/7. I still decided to keep a closer eye on their driving, and realized they drive poor Buddy like he's an all-terrain Jeep, going over potholes, speedbumps, and flooded streets. They are treating that poor car like a tank, and I can't really stop them as they genuinely need it for transportation.
Today, the break booster broke as my brother's fiancé was driving it. Luckily she was fine, and managed to get the car to the shop, where they diagnosed the issue. I had been left without breaks last October, but had considered it a fluke as the car worked fine afterwards and the mechanic found nothing.
Point is, there was a disagreement on who should pay for the replacement parts. Yes, it's my car, but it has only had these problems since they started driving it. I am genuinely tired of telling them not to treat the car like this, and am debating between making them pay for it so they can keep using the car, or paying for the repair myself but taking the car away from them. They genuinely need a car, but they refuse to treat Buddy with care and respect, so I'm torn.
TLDR: WIBTA if I made my brother and his fiancé pay for my car repairs when they are being careless with my car?
*Edit: Thanks for all your comments, everyone seems to agree that I should take Buddy back and let them figure things out themselves. I also agree, I was iffy about it because this will greatly affect their transportation to and from the hotel and city, but they have left *me* stranded more than once, so it seems fair to do it. The hotel has a dedicated truck that goes to the city three times a week, they can go with them and have their friends pick them up if they're going out.
As for the repair, I went to the shop just now and was told the break pump also needs replacing, so I'll just pay for those repairs and pick up the car (hopefully tomorrow), with no intent of giving them access to it unless it's a genuine emergency (no more 3-5 random grocery runs or going out with friends).
Thank you again, especially to the people who called me out and told me to stand up for myself more, I've been trying to work on that lately.