What can i do?

My finace has a 2002 Base models Cavy with an automatic and 35k miles. Her dad has been wanting to know her mpg i was thinking somewhere around upper 20's low 30's. She figured out her mpg and she was getting 21.7 no that is kinda poor i think. Her dad wants me to check the timing and plugs and everything else (filters etc...)After i told him i would i thought about it is the timing even adjustable on that car if even if some how it is off. I was thinking some plugs air and fuel filter and maybe some plugs wires i think it is do for it but what doers everybodt else get for gas mileage thanks

If the timing was off... you'd know it. Change the following... air filter, fuel filter, plugs, wires, run some super concentrated FI cleaner. Your O2 sensors should be ok, or you would be throwin a code. If those don't work start checking for a vaccume leak somewhere or anywhere off the throttle body to the FPR, HVAC line, etc.. if nothing there tell your fiance' to stop gunning it from light to light...

But i'm sure the first few should cure the problem.