I have owned many many gas cars and trucks over the years. I started with diesel trucks in 2002- a GMC 2500hd that did everything and more that I asked of it, followed by a newer crew cab GMC when we outgrew the extra cab. I sold that and bought a 2011 Ford crew, decided I didn't need a new truck and payment, and sold it to buy a 2004 Chevy crew. I have also since 2008 or so been driving VW diesels- a 1995, and a 1997 after someone wrecked my 95. When I got rid of the Ford truck, I sold the 97, and bought a 2013 VW Jetta TDI manual tranny. I say all this because in all those years and over the 4-500,000 miles I've put on these vehicles, I believe and have found them to be more reliable and easier maintenance wise than the gasses I used to drive. The maintenance on a TRUCK can be more costly at every oil change, and filters are a little more- if you know where to shop to get good quality AND good prices.
The maintenance on the cars CAN be less than the gas counterpart. Generally same amount of oil as gas.
Two huge differences are: 1. If you can drive a little conservatively, you can really, really beat the EPA window sticker mpg.
My Jetta is getting 46 mpg lifetime mpg at 12,000 miles so far- estimates were 34-36mpg city, and 41mpg highway!
2. The power is in a much more useful area- 1200 rpm- 2300 rpm. I see no sense in wringing the heck out of an engine, and am quite tired of the gas method of having to mash the right pedal to the floor while it kicks the heck out of the auto tranny to get things done.
I can never see going to gas again as long as there is a diesel option.
Diesels currently run cleaner than gas engines, but most people don't know this.
You really should test drive a diesel, and get it on a twisting up and down road, and see if you don't like the performance better than a gasser.