Want to buy this car and need help?

I really, really like cars and theres this old 1960's or 1970's Impala in this persons drivway somewhat near my house and it's not for sale or anything but i LOVE it, i really like the look of it even though its rusty and i've NEVER seen it moved, do u think if the people held onto that car so long its a testoment to how much they loved it or does it show that they could never get rid of it? I have a feeling its a older couple that owns it and i would LOVE to buy that car someday. Do u think i could make a offer to them? Whats a really good offer price that they'd have a hard time refusing yet im not totlaly ripping myself off here? How would i go about asking to buy it? I'm 16 and getting my permit soon, i will drive my mom's old maxima that i lvoe also, (i get attched to cars) and thats why i want to offer them a good price because i know people get attached to their cars... I would take excellent care of it, plz help. Thank you and no hurtful comments plz