Low gas mileage - 2008 Ford Focus SE Sedan

Clean the MAF sensor. Could also need a tune up, plugs, wires, cap, rotor, fuel filter. Could also have a stopped up catalic converter that needs to be replaced.

tune up. Good starting point.

mass air flow sensor, O2 sensor..... could be many things.

And you somehow expect a 14 year old vehicle
to get better mileage

Besides mileage --what are the many problems you
have with it?

What grade of fuel are you using? There are many conditions that effect gas mileage. The way a vehicle is driven, is it shifting correctly, flooring it to get up to speed from dead stop also known as Jack Rabbit starts, driving with the defroster on when it isn't needed or the setting just above that can be used. Back in the 90's most car manufacturers made a change to their heating.cooling system that caused the AC compressor to kick in when the selector was set to defrost. This puts drag on teh motor and decreases gas mileage. Build up on valves and low compression in the firing cylinders will cause you to lose gas mileage as well. Do a compression check on the motor to make sure you don't have abnormally high compression or low compression on cylinders and use a bottle of gas treatment in your fuel to clean some of the carbon build up from injectors and valves. Also start using the Mid grade fuel. Not the High Octane in your area. In Texas we typically have 3 choices 87, 89 and 93 to choose from. Low grade is enough to run the vehicle but performance is low as well as mileage. I use the 89 octane for better performance and better mileage. The High Octane or 93 isn't really good as it leads to higher carbon build up on the valves. Also check your oil often and make sure your changing it every 4000 miles at the longest. All of this along with making sure you change the Air Filter every 5000 miles will increase your mileage.

Good gas mileage on this car should be 19City 27Hwy. Gas mileage can be affected by many things. Assuming that the car has been recently tuned as you have indicated, I would: Check tire pressure first<-you'd be surprised what low tire pressure can do. Check for low oil level <-engine friction Cheap spark plugs. Let me know.

GAS MILEAGE IS MORE IN THE CITY.WHEN YOU STOP AND GO.THEN ACCELERATE THATS WHEN YOU BURN GAS.TAKES FUEL TO PUT VECHICLE IN MOTION.TRY CHANGING AIR FILTER.CHECK TIRES AIR PRESSURE.CLEAN FUEL INJECTORS.AND CHECK UNDER THE VECHICLE AND UNDER HOOD FOR GAS LEAKS.

Driving habits...incorrect tire pressure...excessive weight in car...low oil/old oil. Many things affect mileage. My 2002 max needed a new O2 sensor. Once replaced the mileage improved slightly.

do a tune up

what is your milage now, how many miles, how does it run, city or hwy driving??

yes dirty filter, tune up, gas additive to improve gas mileage, low tires, there are lots of things to do to improve mileage