I have maintained my Yukon since purchasing it in 2008. I now have a little over 200,000 miles on it. The battery pack was replaced about 125,000 miles. The transmission has been outstanding. The key is not to fool around with puting additives in the transission. It should be sealed. The engine has been soild. I use Mobil 1 long distance motor oil and still change it when i hit 20% oil … usage left. Fuel mileage has ranged from 20 mpg to 28 mpg on the open road. I ran an experiment between Albuquerque to Santa Fe and back. At 80mpg i got 20.8 mpg. I ran the course again holding my mph to 65. I got 24.5. To San Antonio round trip i will average around 23.5 mpg. It varies based on driving conditions, habit and how much ups and down hills. I plan on hanging on to my Yukon. It has been so goid to me may family and dogs. Lol. Great vehicle.