Mileage issue

How about the air filter, spark plugs etc

My 1980 Toyota use to get poor gas mileage when it got older, it seems like when they get older they tend to get poorer and poorer gas mileage, I took my Toyota into the repair shop and no could remedy this problem, or your driving habits have changed, check your driving habits are you speeding up to traffic lights or just speeding in general everywhere, check your tire pressure, low tire pressure can cause you to get less gas mileage or even a dirty air filter can be a cause, if these things don't help then it's age of the car that is doing it and nothing you do will help get better gas mileage.