The average American on-highway trucker drives 100,000 miles per year. I’m not a mathematician, but I’m pretty sure that equates to over a million miles on an engine through a ten-year period. Reliability, ease of repair, and fuel efficiency all play a major role in picking a diesel engine for a trucker, with Detroit Diesel and Cummins leading the charge in those metrics. Despite their common attributes, Detroit and Cummins built their reputations on very different philosophies, which still divide truckers to this day.