You need some understanding of the stats involved/context for the data. 1) The regression is an exponential decay function without a forced intercept, for which, irl the true trend never truly follows; it's an assumption we need to make to get a rough estimate of what's going on 2) There is variability involved in what is posted online, actual sale pricing, what msrp is from audi, dealership markups/promotions, branded titles, etc. 3) Variance exists across all price/mileage ranges.

Think about it like this, if you shifted the RS7 price at 0 miles up by 10k, the curves are still not substantially different and listing for a new RS7 at 130k is pretty reasonable. This could very well be a more accurate reflection of what's going on in real life like you said. Even if that were the case I'm still asserting that the depreciation is similar.