This is what I tell people all the time. It's not miles per gallon I look for in a car but rather smiles per gallon. You can buy a new m X5 for $80k and you'll love the power or for a total of $20k have a fully restored beast from the past you'll love just as much.
You're on the right path researching cost of admission/maintenance. Find a well cared for vehicle and just know that any german parts made of plastic that are over 10 years old should be replaced. If they were replaced recently by the previous owner, great if not you can do alot of the work yourself it's not that hard.
A major cost of the maintenance is people trust their mechanic or shop and don't know about options for parts or repairs.
Prime example.
This guy, thanks to this forum just saved himself a ton of money and headache
http://www.xoutpost.com/bmw-sav-foru...otor-asap.html
The e53 isn't a complicated vehicle compared to a more modern one. Mechanically it's accessable to just about anyone willing to read and try stuff.
I wasn't a fan of X5's before driving this 4.6is and now I kind of want one for myself to see how much power/control I can get out of it. It's planted, fast and for something weighing what it does, dances like a fit and toned baby hippo through traffic.
We have a set of winter feet for it and it did great in snow and ice. I used to live in Mesa CO so I know you get some white stuff over there.
If you find a creampuff and pay $11-13 for it, expect to pay another $2k right off the bat just to satisfy your inner doubts about stuff.
Then there's tires, brakes and a service check to make sure all is well.
Then just budget for an extra surprise fee for little things that break overnight when you're not looking.
I'm giving you a bad case (not worst case) scenario. My '03 wagon hasn't had an issue in a year plus so...?
Like with kids or anything you love and you will love it, the cost just becomes part of the story, the history that make you regret at times and love all the more the other times.
Smiles per gallon buddy, smiles per gallon.
P. S. I'd take $12k today
"You know you want it and yet you fear it. Accept it now before it destroys you! "