agree with slowpoke - WGAF what it's worth when you drive it off the lot? if it's worth something to you, then that should be enough.
i tend to drive my vehicles to their eventual death - i don't look at them as investments and i don't expect to get my money back on them.
my jeep with 150K miles on it probably has more money into it in modifications than i originally spent on it. on the open market it's probably worth next to nothing, a few thousand perhaps - to me, i wouldn't part with it, i've invested too much $ and time and love into it, it's responsible for too many great memories, and it's taken me to too many remote places... none of that is worth a hill of beans to anyone else. so i'm gonna keep it.