Thinking about buying a new straight truck. From the following choices, which would get the best fuel mileage?
2013 M2 106. Cummins ISB with 6 speed Fuller, 260 HP, 4.78 rear end ratio.
2013 Cascadia DD13, Allison automatic, 370 HP, 4.11 rear end ratio.
2013 M2 112 DD13, Allison 3000 HS...