Getting a different vehicle or swapping out the engine aren't options for me. I got a screaming deal on the F250 ($6,500 OTD) and don't want to spend several thousand dollars on a different engine or twice as much as I paid for my current vehicle on a less capable one that won't meet my needs (towing > 10,000 lb fifth wheel several times a year). None of that would make any sense $$$-wise even if the MPG were a bit higher. What I'm looking to do is eke out more efficiency from the truck I already have. I love the Cummins engine as well but let's not start a diesel engine flamewar.
I was more looking for other suggestions that are perhaps less extreme or expensive.
