Until they flashed the CPU against my expressed banning of such procedure (it had original flash from production), I would get 30+ on highway if kept under 75-78 (depending on winds) where it the ECO light stayed on. Premium used with Local CO-OP based ethanol free 91 or Shell 93. I had a high average in rural 4 lane of almost 35MPG flat, no wind, and under 64 or under MPH.
Once the flash happened, best I have done is 28. Typical about your mileage of 27, slightly less in winter (with 19" R-Spec wheels and Blizzaks) . I have 18" Michelin on 5.0 non R-Spec. I am cranked about the morons doing the flash update. Whatever Hyundai did for the CPU flash update, I have soot on the bumper. Also, in town dropped from about 23-25 in suburban driving to 19-21.
I was very pleased with mileage. I keep the tires a few lbs over spec. Better handling, and seems to have less rolling resistance. Also, check the alignment, many came off the boats goofed up when they were tied down. Mine was off out of the factory. Also, Brian was my witness.
One other item. The other picture is of a procedure I do every 10k miles. Knocks off the deposits on the intake valves (PCV blow by, since DI does not wash intake valves with detergent gas)... That also helps. Plus keeps one from eventually having to walnut clean the intake valves.
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If you have not had your CPU flashed, make sure they do not.
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