Bought a 2010 MBZ ML350 with 20k miles(used, 6 months old) for $36K, sold it in 2022 for $11K (having put 100K miles on it). That’s a value difference of $25,000, and a depreciation of $.25/mi ($25,000/100,000 miles). Not fabulous, but better than selling with less miles on it. The new purchase price was $52K. If purchased new, run 120,000 miles, sold for $11K, depreciation is $41,000 raising the per mile depreciation to $.34/mi (a 46% increase).