It's easy to err even if you are trying to set vehicle residuals responsibly. It's hard to predict what a particular vehicle is going to be worth in two or three years coming off lease and ready for remarketing.
There are so many market and economic considerations to take into account in predicting future market value, say people who set residuals, with varying degrees of success.
Those include the potential popularity or unpopularity of a newly launched vehicle or the rate of inflation. Seemingly minor things come into play, too, such as the color of the vehicle. (The average auction value is $12,600 for a white car, $11,500 for red.)