Not only is Tesla guaranteeing that resale value, but Tesla CEO Elon Musk is personally standing behind that guarantee to give customers absolute peace of mind about the value of the asset they are purchasing.
Never mind that Senator Sessions showed absolute and total dishonestly in his press dealings where he failed to disclose the results of the entire study, choosing only to speak of the doomsday scenario that he was responsible for constructing.
Keeping this in mind, you may want to design your own personal benchmark that measures absolute performance (i.e. performance vs. your investment goals) rather than performance relative to the market.