Why has my mpg dropped so much? I'm using the same gas, dealers, same driving. on 2010 Hyundai Santa Fe

I have a 2 yr old Hyundai Santa Fe. Up to the last 6 mos., I got 26 to 28 mpg (higher for longer trips). Now I am getting 20 to 23. Regular oil changes, air/fuel filter changes per requirements. Is there an additive that will actually work and help improve mpg?

by in Murfreesboro, NC on December 04, 2012
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1 answer 3 comments
ANSWER by , December 04, 2012
have you had a tune up done?
COMMENT by , December 04, 2012
Yes. Filters, etc. all regularly changed per warranty requirements.
COMMENT by , December 04, 2012
there is more than just filters involved in a tune up have you changed your spark plugs and get it scan tested for codes.the higher the mileage the less your mpg will be because of wear and tear on your engine I would also trying putting injector cleaner in the tank
COMMENT by , December 04, 2012
You have a point there g.g.,I agree.