<< No matter what kind of car I get, I'll for sure at least get the $6000 back when I sell it (probably quite a bit more) so I see the payments I'll have to make as more like "rent" on the car. >>
That depends...It'll get dings and scratches, and in two years someone will probably spill a drink on the carpet or upholstry, which you won't get out in time, even with the ScotchGard (sad voice of experience...) IMHO, you can plan on your "rent" being at least:
$4k on a KIA Rio or Saturn SL-2
$5k-$6k on a decently equipped Civic,
$6k-$9k on anything else in the $0-20000 range,
over the first two years; if you get seat covers and plan on a $200+ detail job before selling. Since you plan on keeping it in the family, you'd be morally obligated to not take advantage of your sister. She might overlook dings and stains, but your folks won't<G>
Understand, the Rio is gonna lose ~60% of its value, the Civic and Saturn ~30%, and everything else will be somewhere in-between...Are you really certain you want to buy new?
Note kaytwo's post above mine. I hardly consider a car that loses 50-60% of it's sticker price in 3 years to have held its value, but the person from whom she purchased is the one who ate the depreciation. She will probably have a nice driving experience for several years with her Civic, and it'll be worth $4k-$4500 when she sells it...