I have the 2017 1500 3.0 ecodiesel I bought to tow my TT. I hope I didn’t bite off more than I can chew. Is this a money hog as far as maintenance? I have never owned a diesel. Off the lot it showed a 391 range and 29 mpg or so. Today, 3 mos later it shows about 12 mpg and a range of about 290. I’m gentle on the throttle. It’s not a candidate for street races after all. What do y’all think?