just wanna ask is there any way or modifications i can make sa engine or any other parts ko to save gas?

im only getting 8.5 km/l , only 20% of it ang stop and go lahat highway, ako lang sakay ng auto walang heavy loads, 40% lang and a/c use sa bawat trip, slight open windows lang pag 'di naka a/c. pag pwde salida neutral mode nalang.

btw engine is 4g92 lancer glxi '97 w/ 120k+ sa mileage