A clause in just-introduced CO2 rules for new cars that hits 4x2 versions of large off-road SUVs with much bigger fines than 4x4 models will claim some of Ford and Isuzu’s cheapest cars.

The truck that the backhoe is attached to a Ram 3500 Laramie Longhorn Crew Cab 4x4 with a 6.7-liter Cummins Turbo Diesel with 850 foot-pounds of torque, plus an improved transfer case and heavy ...