Further more...
Right now with fuel prices, and newer efficient direct injected gasoline engine fuel economy coming close being on par. Specially when the initial extra expense $$ of a diesel engine option- it would take a long time to break even on fuel cost over the years. If you have costco near by, gasoline is 4% discounted and where I am - diesel is not an option to purchase at Costco.
The only thing diesel have going for it is power/grunt and fuel economy.
I think it depends on where you're located and what your driving habits are. Right now around Ottawa, diesel is often 7c/L cheaper than 87. This changes in the winter, but the price is still within a few cents of RUG. In Texas, I completely understand. I was there a month ago, and RUG was often cheaper than D2.
For Canada the price difference between gas and diesel engines was about $2k.
[Lots of math ahead]
Statscan fuel cost averages (July 2015 - June 2016):
RUG: $0.998/L
D2: $0.966/L
http://www.statcan.gc.ca/tables-tableaux/sum-som/l01/cst01/econ152g-eng.htm
I'm currently averaging 3600km/month.
My current consumption is 6.3L/100km lifetime (about 1L/100km above Fuelly average for 2015).
This leads to an average monthy fuel cost of: $219/month
With an equivalent Corolla or Mazda 3:
Fuelly consumption is 7.2L/100km.
I'll use 8.2L/100km to better match my driving habits compared to Fuelly.
Gas equivalent average montly fuel cost: $294/month
Maintenance wise, they're relatively close (excluding DSG). Considering the Golf's maintenance interval is about double of a gas equivalent. I'd think the $900/year I'm saving in fuel would easily cover the difference in maintenance. Heck, this'd cover the engine difference as well within a few years.
VW Dealer:
15k km Service - $250.32
30k km Service - $539.11
60k km Service - ??? + DSG ???
...Repeat until...
195k km Service - Timing belt (Estimated $1500 or so)
When I bought my car, I roughly estimated the 5 year maintenance cost to be around $7000 (at the dealer, no missed optional services, 200k km on the clock). I'm also not counting DPF replacement, though I'll factor that into the 10 year cost of the car based on my driving mileage (500k km/310k miles). Breakdowns are also not factored in, but I'd expect the cost of them to be greater than on an equivalent Mazda/Toyota.
Mazda:
8k km Service - $130ish + Tire rotation (extra)
24k km Service - 8k service + brake inspection
40k km Service - 8k service + Cabin air filter
...
https://www.mazda.ca/globalassets/en/pdf/maintenance/mazda3maintenance.pdf
I'll take a better look at the Mazda service costs next time my Miata needs a part.
Insurance also varies wildly, my golf was $10/month less than a corolla or mazda 3.
Bottom line, diesel is still a more economical choice depending on location and driving habits