Hmmm… let me throw another wet blanket on the plan.
Why do you need a car at that age? If you’re making that kind of money without a car, why not just keep that up? Keep doing the same things that are working to generate that kind of savings, and instead of buying a car (a declining asset that will eat up even more time and savings after you buy it) learn to invest your savings.
If you put off the purchase of “a car” for awhile (I know how anxious you are to drive; I’m not so old as to have forgotten) and if you learn to invest well enough, and with enough discipline, you could get to a point in a few years where you could buy an even nicer car with investment profits, and continue to have capital to invest.
I know a 14-year-old boy in my neighborhood who has a lawn-mowing / snow-clearing business with three employees, last time I talked to him (a couple of months ago). I haven’t asked him about his savings, but I do know that he’s buying better and better equipment all the time… for cash.