2001 Silverado with 4.8L V-8, automatic, 2WD, no performance mods - it's all completely stock.
I do almost nothing but city driving and get 13.5 mpg. If i take a road trip, say Dallas to Houston, I'll get 16.5 mpg if it's all highway.
Consider, I do have the added weight of a bed liner, loaded tool box and over-sized all-terrain tires.
1998 2wd 1/2 ton Suburban. 21 mpg pure hy 60 mph 12 mpg pure city short trips 15mpg pure city(mild hypermiled-pulse glide)
21 mpg on 3000 mile Hy trips-set CC to 67 mph-on 70-75 mph interstates(2000 miles or so)-New Orleans to Flagstaff
59 mph on Hy 287 (Tx)-700 miles
45 mph road work-maybe 150 miles
35 mph in small towns
60 mph actual driving speed average(-1200 miles- at well above sea level-which improves mpg)
45 psi all around-syn oil Mobil 1 10w30 -syn diff lube 75w140
2007 Silverado (New body) Ext cab short bed z71 4x4, 6.0 Vor. Had 245/75/16's for the last 2 yrs.
just put on kelly 265/75/16.
Over all, 12.2 mpg. tuned superchip gas saver, K&N air filter.
don't really haul much, 8x12 once a week with lawnmower.
mileage is a good mix of city, stop & go and hwy.
2005 Chevrolet silverado 1500 ext cab, standard bed. V8 4.8L 294. Flowmaster series 40 muffler, 265s on 17's. 15hwy and 13.3 city
Keep it going. Who's next?