I have a 95 3.0 LS with 230,000 miles on the odo. I have owned it for 10 years....second owner. I have always gotten about 15 maybe 16 mpg on regular fuel. Doesn't seem to matter if I am on the highway where I am almost always pulling a trailer and motorcycle,...or in town,....or across town.....I generally drive pretty aggressively......probably full throttle acceleration about 50% of the time. I run 33" tires and keep it in "Power" mode all the time ( the 33" tires made a huge difference in the trucks acceleration away from a stop and also speedo reading went from bing about 5 mph high to 2 mph LOW)