09 Cobalt with bad gas milage!!!! HELP!

[chevrolet25]

Ok so i bought this car almost a year ago and slowly noticed a decline in gas milage. I have never got past 30 mpg and i have a 2009 LT2 sedan with 2.2., it has ss 17" mag wheels with the stock pirelli tires. Its not turbocharged or supercharged and completely stock!!! i recently bough and K&N cold air for it to see if it would help and nothing! now i recently had it in the shop for a knock in the suspension and after several times in the shop, now its getting worse!!! now mind you, i drive ALLLLLLLLL highway 50 miles a day at 65 and im lucky to pull 26mpg, im averaging 24 right now. Im lucky to get 250 miles on a tank and if i do, its burried in the RED! it has fresh oil in it now and is always on time for service. Tire pressure is good and 09 models have the fuel filter inter-graded in the fuel pump, so i cant change that. I checked the plugs and i thought they looked fine. no carbon build up and smelled like they were burning clean! i have ran probably 5 quarts of fuel system clean out and injecter cleaner GM BRAND!!! i always run chevron fuel! o and heres the kicker!... If i run premium fuel, i get worse milage!! WTF please help me guys any inpute i will consider i cant afford to pay 95 bucks an hour for a shop to diagnose the problem! im thinking they did something when they had the suspension tore apart, but it does not pull so i would assume the alignment on.... thanks

---------- Post added at 01:07 PM ---------- Previous post was at 12:56 PM ----------

o yeah and the car just rolled over to 40,000 miles

 

[reyesa21]

i hav the same exact yr lt model. and i get bout the same. i dont know if it is what its supposed to get our not but yea i dnt like it. mayb its jus sedans but i kno tuning it will help. i hav yet to tune mine but i will soon

 

[chevrolet25]

well that makes me feel a lil better and that your getting sh***y milage too! lol jk but yeah i donk know. Someone told me that it could be that my model is fully loaded with every option puts on some weight and it being sedan compared to the base LS's they get the so called epa reading from........
And aww you have black!!! i wanted black so bad but all they had was white in that trim

 

[sfwg]

get a tune problem solved...i get 360 mi off of a tank=30mpg trifecta tune ftw(that tune was just to get more power, remove throttle delay,get rid of govnor)

 

[cobalt123]

tune it your problem is the premium fuel. the stock 2.2s are not flashed to use octane higher than 87. tune it for the higher octane or go back to 87.

 

[reyesa21]

how do you tune it? is it tht lil device ur plug in?

 

[chevrolet25]

i dont use premium fuel all the time, i tried it just that once to see if it would improve my milage, and obviously didnt.........

 

[cobalt123]

how do you tune it? is it tht lil device ur plug in?

tune it using a trifecta tune...it plugs into the obdII data port

 

[chevrolet25]

So how do i get my hands on one of these trifecta tune devices?

 

[Intmd83r]

how much is the tune thing ? right now im at 11mph avg speed and getting 18mpg lol