First of all let me tell you my cars are 19 years old and paid for. They all have in excess of 100,000 miles on them.
I put about 600 US dollars into them each year.
A lot of the money spent goes into up-grade types of repairs. For example, when the clutch needs replacing, I up-grade the fly-wheel and clutch to a aftermarket unit for performance reasons.
So I could be by with less, and most of the work done this year will last another 10 to 15 years. So for my cars (1990 Miata's), I could get by with less. But why not make the car better instead of being happy with stock?