I only recently purchased this K1500 Suburban SLT from the original owner, so my experience is "short term". It has over 285K miles on it (yes 285,000) and still runs and drives perfectly. Most of the miles were freeway miles- which helps. I was told that the engine is original, but the tranny was replaced 100K miles ago. I have only had to install a coolant sensor- which was only $70.00 to repair at the shop. I have not driven it enough to see exactly what the mileage is, but I am sure it is not that great. I will probably never need all of the space, or need the 4WD, but nice to know it is there if I ever need it. I also really like the styling of these trucks.