The requirements were: fully adjustable heated bucket seats, the best suspension you can get for the money, AWD, traction control, enough power, auto tranny, handling (should not wear you off during your 2-hour commute), 4-door sedan, reliability, etc.I don't understand the correlation between your wife's bad back and the car she drives.
In 2004 the options were: 330xi, A4 and obviously the G35x.