I say hold out until you are 18 and sell at least 1 of the other 2
while you wait you can save some more $$ and maby not need any help getting a loan
Keep in mind that you ahve no credit history so they will screw you with th interest I would gess something like 18% or better and you will need to have a cash downpayment of 20% of the loan +TT&L
If you want to avoid getting screwd on the car loan then hear is what me and my wife both did at your age ,and it is very hard but well worth it
as soon as you turn 18 get a credit card it does not matter from who and the interest dont matter either
charge up at least $200-$250 a month on it but pay the balance off every month NEVER late and always the balance do that for a year maby 2 this will show creditors that you can and do pay your bills in that time join a credit union they give good rates to members not realy the best but after a year they will loan you money for a car if you have credit and you will with the credit card in your name then go buy your car and keep up the same deal with paying on time every time
The end resualt will be great credit trust me me and my wife are in the 1% of car buyers that get the 0% for 60 months on new cars
If you rush it though you will get screwed trust me I know a guy who makes almost as much money per hour as I do pays less than 1/2 as much in rent/house note as me and because of bad credit he can't finance more than $15K no matter what he puts down co he drive a scion xB and I

to my self cause I told him when we were around 18-19 and he had 2 credit cards maxed out that he was messing up big time
by the way he is 28 and still paying for te junk he bought back then
good luck
Jason