im turning 16 and need a car within a month. my dad has an x5 and needs it so i must get my own car. for the past 4 years ive wanted an M3 but me and my dad agreed i need a 4 door car. im looking for a 4 door automatic M3. he wont buy me anything over 50,000 miles and it can't be over $23,000. now he wants me to get an A4. its not a bad car but i want an M3 . anyone with an M3 over 50k miles and no warranty do you have a problem? also what does CPO make a difference and if i purchase an M3 with lets say 60k miles and no existing warranty can i get the 100k mile warranty? how much does it cost, what doesnt it cover, and how does a car qualify for CPO. should a non CPO vehicle be worth less and are CPO and the 100k warranty worth it? would a 70,000 mile vehicle with a 100k mile warranty be a good investment? thank you