Whether this statistic is even true is hard to know, since the Times lifts it from a class-action lawsuit against auto dealers. The study prepared by the lawyers relies on Tennessee data on car sales, but the lawyers independently categorized the buyers by race. That would never stand up under peer review because they had a clear interest in associating blacks with the higher markups. Even so, the claim that racial bias is the operative factor is absurd on its face. Ah, you say, cars are bought and sold through a process of negotiation.
Car dealers try to get top dollar from every customer and buyers try to get the cheapest deal.
If dealers weren't able to cadge that extra charge from as many non-black buyers, it's only because they can't. It doesn't exist. This is just a guess, but a deeper inspection would probably confirm that dealers use the markup to turn a profit on what would otherwise be unprofitable transactions. Sure, some dealers may harbor bias against blacks, but green is green, and perversity doesn't apply to large numbers. The Times offers nothing to rebut the strong presumption that dealers on average treat everyone the same, plucking each buyer to the maximum extent possible.