Tesla would steadily accumulate less desirable cars. That looks bad, and is bad for cash flow. Tesla makes a nice margin on the more desirable CPO, and unloads the rest a near cost. Since they took these cars in trade for a new vehicle, it is all good. Tesla practice is likely industry standard, especially in luxury brands. Neither Tesla or BMW want a huge lot of used cars eating up capital and steadily depreciating. Every premium car maker will forgo low margin sales to preserve the perception of exclusivity.