That said, if you take a look at pp. 13-14, there's an interesting comparison of the Ford Crown Victoria and Mercury Grand Marquis. These two cars are identical except for minor trim and decorative elements. Virtually all police cars are Crown Vics, and virtually all Grand Marquis buyers are grandmas and grandpas. Police duty serves as a workable proxy for the kinds of risky driving attributable to testosterone poisoning; look at its effect—it pushes the Crown Vic way up the Y axis! So, perhaps thoughtless behaviour behind the wheel does influence the real safety performance of trucks.
You begin to see how complex this all is…?