financing a truck and goin into military?

[xist2spire]

im turnin 19 in a few weeks and have saved up enough for a down payment on a truck. i do not wish to wait any longer as i really want my own vehicle to go where i want instead of having to use my parents car. i do plan on enlisting into the air force between 3-6 months after i graduate high school. My parents dont thing this is a good idea. they want me to keep savin my money then buy a car with a full payment. I however, make enough to pay my bills and cannot wait any longer then what ive already waited to buy my own vehicle. should i do this or not?