I had a Ford F-250 with a 428 cid engine. This truck had no problem getting 25 mpg with a 6200 lb truck. I had a shop where I could check emissions and build the engine to perform at its best. In the late 70’s it passed all CA standards with ease. If I could do that, why is the car company’s having a hard time breaking the 40-50 mpg with much lighter cars? It has allways looked like the car company’s were being paid off by the oil company’s.