My reasoning behind wanting a diesel to be REALLY honest is the absurd ease they are modified, the 100 I own is grossly underpowered and even the 200, while much better could stand to have another 200hp and 300ft/lb
However with that said, if you take a look at other diesel vehicles - like the toureg - the diesel vehicles hold their value considerably longer and trend to have LESS problems.... Over all their gas mileage is 30-50% higher than the equivelent gasser....
I'll be really honest with you though, in America Diesel engines are often over priced, if you continue on with the Dodge example, the 6.7L cummins is a 6k$ premium, and even at the unloaded MPG of 22 (what i get with a chipped truck running 35" MTs) , you'd be better off buying the Hemi for 6k$ less and getting 14mpg at least until you get to about 98K miles - if you drive like most people and only get 17-18mpg it would take over 315k miles to recoupe the cost on gas alone - Now that's not including the change in maintenance intervals and and what not but over all assuming current gas prices (3.50/gal for regular and 4.15 for diesel) if you buy a 2500 cummins over a 2500 hemi at 309K miles you would break even... Again this accounts for nothing else other than the premium in cost - the retail resell value alone allows you to recoupe a lot of that value with in a year a two...
Over all it's a terrible decision to buy a diesel car/truck right now, but the same can be said for hybrid... a loaded prius is nearly 31k$ - a loaded corolla, with more room is about 20 if you assume 28mpg for the corolla, and 48 for the prius you have to drive 212000 miles to get the money back...
There are some vendors that are a little bit less drastic, buying a VW TDI versus an equivelently equipped JEtta or Golf is only about a 1500-2000$ premium which you can recoupe in 78k miles, but even then - most cars in America are bought and sold in 30K mile cycles
There are only 3 good reasons to buy hybrids or diesels right now
1. They lose value slower... This means you must keep the vehicle beyond the initial depreciation cycle.
2. You actually care about the environment and can afford to basically throw the money at the problem
3. you NEED the function of the diesel engine, which means you need the power and torque provided.
it certainly is not a good economic decision or a wise financial planning decision for a short term purchase...
Sorry for the windy reply...
-Z