Make SURE you get the 3.5, the other motors are all gas guzzling dogs.
These things are NICE but they love gas too.
The worst things i can remember about them, is brakes, and there was a few that had a rear axle seal go out on them in our dealership (no big deal - new seal and set of shoes).
Other than that, they really are die hard. do her a favor and get the bose system.

(tell her i opted for that for her...lol)
In all seriousness, they cant be killed, they're GREAT! Altitude wont bother it - that's what fuel injection is for, it will adjust itself for changing altitudes as she drives (if she comes out to sea level to see you or something).
Good luck on finding a used one, NOONE sells these in my area because they're really nice and will live forever.