living in ny i get poor stop and go mileage around 15, but on the highway 26 or so. many things affect mpg. tire pressure, u should check that and keep them up to spec. i use synthetic oil which u should consider , that would give a small increase as well. i think the rapid fire plugs , pcv, oxygen sensor, and air filter all are major items. plug wires etc. remember our reattas are heavy and the 3800 a large six so u cant expect miracles. good luck i love mine.