So to start things out I'm tired of 13 mpg with the 4.0 especially with gas being almost $5 a gallon. I ran some numbers on https://www.fueleconomy.gov/feg/savemoney.jsp and a diesel is just more economical. In my calculations I set diesel to be 20% more than gasoline. As for the estimated mpg, 15 for gasoline and 22 for diesel as to be on the more conservative side of things. Diesel comes out on top for cost savings which is a major motivating factor along with the possibility for increased driving range. The project is just starting as I picked up the engine and it's harness earlier this week. I hope to keep this project well documented so others may find it useful in the future.