Originally Posted by RockRunner
Also as Corbet mentioned the PM can be costlier.
Not as much as in the past though. Dee's ML320 has a V-6 CDI diesel. The oil capacity on it is only 2 qts more than the gas version, and just like the gas version the oil changes are done at 15K intervals. It has 100K miles on it and other than routine oil/filter stuff the only other cost has been replacing a cam position sensor which was $100.
If you are deciding purely on the cost/benefit analysis, get a gasoline rig. Regular gas will always be cheaper, the up front purchase price is less and they are easier to get serviced reliably at more locations.
But if you want better performance at elevation, especially if you will ever tow with the rig, I would go diesel.