I apologize for the long post in advance, but read it you may learn something, and if you dont, I apologize twice...
The problem here is we are in the us, and we dont have 100mpg diesel cars available to us, and if you google that vw diesel motor you will see a lot of unhappy customers with sub 100K on them...
You are very lucky with your 6.2 if I remember correctly them were terrible engines, {i had a 6.5 that was also a junk box, replaced at 90K.} the 6.2 was naturally aspirated and got worse mpg than a large gas job {And is a smelly loud diesel}... I am very mechanically inclined, I built my own oil trucks from school bus chassis's for years until business built up enough to warrant a new truck {at $139K its not something you jump into, but before I sold that portion of the company I owned 6}. I have rebuilt more DT466 engines than I care to admit, from old rotary pump models to new digital gap models..
But anyway, the problem is diesel is 50 cents more per gallon at the pump, the parts cost more, the labor costs more, and parts are tough to get {not many sold, so not many in salvage yards, and the ones that are there all have the same problems}... Plus not every gas station sells diesel, sucks to find out when you are on E...
So, this is where people run into trouble figuring how to save money...
I own a couple HVAC businesses and I will try to explain this as well as I can with something I see all the time...
A customer calls me up and wants a high efficiency boiler... Great... I go to the house and sell them a Hi eff. boiler, but always tell them, "you are much better off with a quality standard boiler vs the high eff units in the long run", but you know what they buy, the high eff. units, 99.9% of the time.. To save money? Cant be because they cost more..... Heres why...
a nice Budurus natural draft boiler {cast Iron 120K btu wet base} costs $2900 installed and gets 86% efficiency with very small stand by losses and will last 12 years with 0 service costs, at 20 years avg, service costs are under $600, and the boilers life span with a filtered water supply is 35 years.
Now a Budurus high efficiency gb series, installed costs around $7900 and gets 95% eff., also has low stndby losses, but Will cost $1600 in service before it is 8 years old!!! And the average life span is 13 years!!!! {before service costs will warrant replacement!!!}. Lastly the parts are not stocked, they are almost all order only availability, so when you call because you have no heat on xmass eve, guess what, Ill be back the day after new years to fix it, if you are lucky and the part is in stock at the warehouse in Germany} Buderus is also German, pure coincidence..
So lets do a little of the math, in 26 years {sounds long but keep in mind most peoples mortgages are 30}, the high eff unit will cost you around $20,000 and need to be replaced again because that is 2 lifetimes!! If you have a 3000 sq ft, std insulation home you will save around $210 per year {which is 9% off of what you would spend with a std boiler}, so over 26 years you will save around $5400- still with me? $20,000-$5400=$15600, thats what the system costs you after you minus your energy savings...
Now for the standard system- at 26 years, you would have spent $3500 on the boiler and service {but lets call is $5000 for good measure}... Add that to the $5400 in extra fuel costs, you get $10400 and the boiler still has a half decade of life left in it !!!!! So that means the high eff. unit cost you an extra $5000 and needs to be replaced after 26 years!!!!!
So IMHO that is what is wrong here, people dont look at the entire picture... My friggen powerstroke diesel service trucks cost me so much in repairs its stupid, vs my chevy powered gas vans cost 1/10th that in their entire lifetime... And any mechanic can work on them, doesnt have to be a certified specialty mechanic... Plus the diesels initially cost $10K more!!!!
If you are worried about gas mileage, get a prius, I bought my wife a brand new one in 07 and besides a pair of headlights {that I blew out trying to jump start it} it is perfect still, not one service problem}, and she gets good gas milage... But for the money a brand new car like the chevy I mentioned earlier is your best bet, find a dealer, work him over to a couple thousand under cost, and walk away happy knowing in 5 years, you saved a lotmore than a diesel would have saved you...
My grand father used to say "penny smart dollar foolish" and I see it a lot, People spend $5K extra to save $2K in the long run, not smart...
I am very serious about my money, maybe that is why I am comfortable and will retire before I am 40...
, I never had to do anything illegal or immoral, and started with a $12 an hour laborers job, no parents to hand me a business or pay for my education, 100% ME, just hard work, smart decisions, and a table spoon of common sense...
So anyway take my "free" advice or dont, and good luck with the new car, I am always in a good mood when Im buying a new car, to me its more fun than a vacation, because I usually have more to show for it than a few pictures and a sun burn in the shape of a pool side menu {long story, dont fall asleep on a sunny windy day in Peru, a hologram menu may fly by and stick to your back} thats more free advice for you, Im not even going to get into how I gut the sun burn on St Thomas, when I thought we were on St Johns the entire trip {in my defence they are close and share an airport}...