I guess I should be clear that I have taken a very proactive stance on repairs and maintenance... I have the car looked at every other month or so and when my mechanic finds problems we fix them immediately.
This has made the car rock-solid dependable for long trips.
I've replaced a radiator fan, coolant overflow tank, oil filler tube, the tranny, and two control arms since I bought the car. The tranny was a result of abuse from a previous owner though... not a defective or failing part.
All the rest of my expenses have been made to beautify the car. My most recent addition was the rear diffusers, which added a modest 25 HP