i done all these and still get 15mpg....Change sparkplugs, rotor cap and button, ignition coil, plug wires. Change all fluids. This should fix it.
drive at 55 on the highway, never brake, anticipate redlights so I can coast then get back on the throttle without braking. Take corners harder and not brake and keep momentum. Slow down going up hill and speed up going downhill. I'm going for 500 on this tank. I have about a gallon left and I'm driving all highway miles tomorrow as well. I also have done some aero mods, have green-x tires, and the car has some random intake and manifold.Dang. How'd you get so much on one tank?^^^ the best I've gotten on a tank is 229 miles.