1\begin{tabular}{lrr}2\toprule3Step & Remaining & Dropped \\4\midrule5S0 all listings in snapshot & 273\,265 & -- \\6$-$ kind != auto & 271\,992 & 1\,273 \\7$-$ VIN duplicate (non-canonical) & 259\,133 & 12\,859 \\8$-$ model year outside [2005,2026] or missing & 256\,651 & 2\,482 \\9$-$ mileage outside [1000,400000] km or missing & 249\,958 & 6\,693 \\10$-$ entry price outside [2000,250000] \$ or missing/placeholder & 241\,321 & 8\,637 \\11$-$ make or model missing & 241\,298 & 23 \\12$-$ uid identity collision \hfill $\Rightarrow$ S1 (all sources) & 241\,297 & 1 \\13$-$ sampled portal (autotrader/cargurus) or private marketplace (kijiji) \hfill $\Rightarrow$ S1 hedonic & 136\,393 & 104\,904 \\14$-$ flickering/failed connector or small portal & 128\,144 & 8\,249 \\15$-$ oscillating price path \hfill $\Rightarrow$ S2L & 128\,091 & 53 \\16$-$ left-censored stock (day 1 or source start-up day) & 80\,856 & 47\,235 \\17\bottomrule18\end{tabular}19