i used to have a 99 v6, that only got 19 mpg highway, about 12 city with new plugs, wires, and filters. I ran a can of seafoam in it 2-3 times and it improved abit, but nothing near what its suppose to get new, but thats just it, its a used car, their is to much buildup and **** in the engine to get "new" mpg, and also note the 26mpg highway is at like 45 mph for the test, while going downhill, in like a vacuum tube so no air Resistance 
