First of all, explain to us why you need such a nice car as your first vehicle?
That's a great point. I have a great car for my first, and I bet insurance costs as much as that audi or more for liability, but it is a much cheaper car. Cost only $3000 a year and a half ago. It is great, probably faster then that audi too, haha, but for a first car, it has plenty of project potential without breaking the bank again, and cost 1/4 of the price of that audi.
I'm sure your dad already knows all the reasons to buy a car, and everything you will come up with, is just him seeing how smart you are. The only reason you NEED a car is... well, there isn't one. You won't go home earlier to do homework, and won't swim much more then you do now. You will go out more at night, and spend more money. But having a car is great... Having a car makes everything easier, having a 12k car makes everything harder. If it was my first car, I wouldn't get something so expensive.
And you say project car?!? No way man, you are in high school, and the expense of the car will be enough... Putting a turbo to actually make that thing move decently, will be at least a good $2k. Nitrous wouldn't be too bad... but power is expensive. Even more so on new cars, and much harder. If you want a project car that can run and drive, get something from the 80s or 90s. It's your first car, I wouldn't recommend and audi.