Parents got me new car, I feel very unprepared. AITAH for not being grateful enough?

Hi, I’m 15 years old. I’ve just started to learn how to drive a month ago. My parents and I were talking about cars, but there was little to no talk about getting one for real. Then, they surprised me today with one. I barely even know the basics of driving, haven’t even taken my written. I was thinking this would all be postponed till next year. I’m really scared as well, since the gear shift is completely different than the car I’ve been practicing on. This is a huge investment, and I am grateful, this is just really not what I was expecting especially for my first car. I thought we would all go together and pick one out when I was ready, which is definitely not right now. I feel it’s so early for all of this and I definitely wanted more time to decide. My parents are very mad at me for not being as excited as them. AITAH?