Within the past 2 months my MPG has dropped almost 6 mpg and I cannot figure out why. I tried a new gas station in case ofbad gas, oil changed, air filter good, tire pressure is good, no smell of gas leaking. My dad and some mechanics say its from winter weather but I dont believe it. The MPG dropped after winter had already started and I have had this car for 4 years and drove it in cold winters and the MPG was never affected and I also lived in FL for 2 of those years and had the AC blasting all the time and still this never happened so I refuse to believe its the weather. Any Help?

 

How old is the car and how many miles do you have on it? it may need a new fuel filter.

 

Its a 2003 and about 89,000 miles... I thought that too but I was told that the car wouldnt be running right if it was the fuel filter, I dont know[]

 

this just recently happened to my cadillac. after inspecting a lot of things, i got to the fuel filter and it was somewhat clogged. i was getting 11mpg, and after changing the fuel filter i am now getting mid 20's for mpg.

 

When is the last time it was tuned up?....spark plugs, fuel filter(and yes it WILL effect MPG without driveability issues), injector cleaner, throttle body cleaner, air filter

 

Another thing to consider is whether or not the gas you are using contains ethanol. For example, BP's gas typically contains up to 10% ethanol and for some cars, it can negatively impact gas mileage. I'm not saying that this is the ONLY source of your problem, but it is definitely something to consider. Some cars just can't handle it. I would definitely check into a tune-up though. Platinum spark plugs are a good upgrade if they need to be replaced, and the fuel filter is definitely worth checking into as well.

 

Well I changed the fuel filter and it was partially clogged I guess, thats what my mechanic said and he also said it was shifting funny almost like it was starting out in 2nd gear but I took it to an actual GM dealership and had them look at it and they came up with nothing, said it was the weather... he did mention a tune up so that will probably be my next route?

 

Well I would definitely go the route of a tune-up, it should help. That would include, but is not limited to: spark plugs, wires, cap and rotor (if applicable) fuel and air filter. And it wouldn't hurt to do a fuel system cleaner on top of that... although some of them are just crap in a bottle... Aside from that, you really and truly need to go to a Mechanic that you trust is not going to screw you over and have them run a diagnostic on your car. Hooking up a computer to the car will show any specific problems that exist. A tune-up should be specific to the make/model of the car itself, and the age & mileage also have to be taken into account. If you look at your Owner's Manual, it should have different milestones of age / mileage and what needs to be done at those times. It's always a good idea to keep on top of those manufacturer recommendations. Hope this helps, but let us know what happens, or if you have any other questions.. and good luck!