Can heuristic information processing affect important product markets? Analyzing over 22 million wholesale used-car transactions, we find evidence of left-digit bias in the processing of odometer values, whereby individuals focus on the number's leftmost digits. The bias leads to discontinuous drops in sale prices at 10,000-mile odometer thresholds, along with smaller drops at 1,000-mile thresholds. These findings reveal that information-processing heuristics matter even in markets with large stakes and easily observed information. We model left-digit bias in an inattention framework and structurally estimate the inattention parameter. Empirical patterns suggest the results are driven by final customers rather than professional agents.

We investigate whether the first digit of an odometer reading is more salient to consumers than subsequent digits. We find that retail transaction prices and volumes of used vehicles drop discontinuously at 10,000-mile odometer thresholds, echoing effects found in the wholesale market by Lacetera, Pope and Sydnor (2012). Our results reveal that retail consumers devote limited attention to evaluating vehicle mileage, and that this drives effects in the wholesale market. We estimate the inattention parameter implied by the price discontinuities. In addition, our results suggest that estimating consumer-level structural parameters using data from an intermediate market can give misleading results.