A good resource is gasbuddy.com
, just plug in the zip code of interest and get revently observed prices for reg., mid, premium, and diesel.
Agree the option is best for someone who would have a Hemi otherwise and not so vs the flexfuel V6 for someone who does not drive a lot. Around here the cost for diesel is about 12.5% more than reqular and 6% more than midgrade.
Also think that other than the faux-greens whose other car is a Prius, the real market is for a workhorse and not a GALB. Once production catches up to demand I suspect it will become an option on the Laredo "E", just takes a checkbox on the computer. Q3 or Q4 perhaps when the Cherokee is introed, suspect it will take sales from the Grand.
Taxes can also vary widely between states. Figuring all of the taxes on a gallon of gas or diesel (Federal, State, Sales, underground storage, "component b") would take an accountant and comiled lsts often leave out elements (most confusing is California which seems to differentiate between Inter and Intrastate for diesel).
Bottom line: in 2013 not only do the ultra low sufate lrequirements have an impact on diesel, it also seems to be taxed higher than gasoline. Double whammy.