I think the diesel advantage is going to become less and less of an issue the more they tinker with the fuel formula and as they add emission controls to diesel vehicles. As it is right now, with diesel running about 30% more a gallon than regular, it takes a big mileage improvement to make that up. And you are polluting more. Let me take all the pollution controls off my F250 and I could probably get diesel-like mileage out of it too.

 

Diesel is more efficient than gas. Or more accurately, the diesel cycle is more efficient thermodynamically than is the otto cycle. So even without your pollution controls, you will not get diesel mileage.

It does seem likely that increasing the pollution controls on a diesel engine would also reduce the mileage, but I haven't heard any actual numbers, and would still expect to see the mileage delta.

 

Maybe, maybe not. In the 3/4 ton trucks there isn't really a huge difference in mileage to begin with. The difference is with the towing capacity and performance - low end torque mainly. There are so many improvements that could be made to any vehicle if we weren't restricted by emissions testing. Until they get serious about diesel emission testing, a good amount of the advantage diesel vehicles have is unfairly maintained. Heck, if I could run straight exhaust, non catalyst like the diesels do I could get a huge boost in mileage.

Once they start implementing the clean burning diesel fuels (this week in MA if I heard correctly) which will lower the energy content of the fuel, go look at the diesel boards and watch the *****ing begin. It will be like this board when we started getting the ethanol back in the spring. Although a 5% reduction in efficiency will be harder to notice at 13 mpg.