AITA for not giving my mom my old car?

I’m 16 and I got a car a couple months ago. It’s a pretty nice car, for a starter car at least. <br><br>I have 2 siblings; a 6 year old sister, and a 21 year old sister. My older sister is moving out and she doesn’t have a car, so my mom asked me if I’d give her my car and she’d pay for a new one for me. I said no. <br><br>I saved for that car for a long time, and I’m not giving it up to my sister just because my mom wants to put her through college with minimal expenses on her. My mom got mad at me and said I was selfish. AITA?<br><br>Edit: age 6 is my younger sister, not 16. <br><br>Edit 2: I didn’t buy the car, my father and I chipped in for it, and it was a used car from my uncle.