It turns out that Stout Risius Ross>, the financial consulting firm that conducted the study, didn’t have access to any proprietary data. Instead, they used recall filings and the manufacturer-level data available in financial statements. Recall filings include the number of cars affected. Annual costs of warranty claims must be disclosed in financial reports. These data tend to be messy, as different companies include different things in these costs; there’s no precise universal standard. Also, multiple model years are often lumped together, and changes in both warranty claims and recalls lag changes in the number of cars sold. Keep these limitations in mind when viewing the “warranty claims as a percentage of revenue” comparison.