>>82049535 (OP)
>Every few years
To keep up appearances, and/or avoid the inevitable problems that will arise the longer a car is owned and used. I had to get rid of my car that was built and released in 2006 in March of this year because, despite everything I did to keep it alive, it finally crapped out to the point of not even turning over (even with a relatively new starter). The cost to repair it exceeded the value of the car itself.