hello, speaking as a diesel engine mechanic, this is exactly what modern emissions controls have sadly become. professional drivers (truckers) want to cut out

hello, speaking as a diesel engine mechanic, this is exactly what modern emissions controls have sadly become. professional drivers (truckers) want to cut out all the emissions control systems because "older trucks get better mileage!" On the face of the issue this seeems to be true, but even after cutting everything out and switching back to low-grade diesel all you've done is create a smoke and soot belching mess from the 1960's. Why is this? Two reasons: older trucks got great mileage because there was less traffic congestion and fewer weigh station stops, and the national maximum speed limit law in 1973 made sure trucks drove a speed that got great mileage.