We drive our auto trans Sonata with the ECO light showing over 90% of the time. No fast starts or hard acceleration. Can't really think how we could drive it more efficiently. I didn't say we get terrible mileage. We just don't get near what was heavily advertised by Hyundai. Overall we average between 10.5 and 11 litres /100kms through all seasons. I think it should be better and I think Hyundai errer on this car as they admitted to doing on every car since except the sporty Genesis Coupe with turbo.
FWIW, when my wife drives my car, i notice the fuel economy reading is usually in the low 9s...i drive it, it's in the low 7s now (that it is cold out)...i don't pitter patter around, but my guess is she does a lot of gas/brake/gas/brake/gas/brake...i give it gas, and coast to the red light, stop...give it gas, cruise at the speed limit, coast to red light, brake...i don't know...i don't drive like a 90 year old man, and she doesn't drive like a speed demon, i think she is just heavier on the pedal than i am, which doesn't result in any faster driving, just using more gas.