The Sonata has an ECO button on the dash and when it is pressed in does something magic, I think (because it isn’t covered in the owners manual that I downloaded from Hyundai), to the throttle response and shift points to increase the car’s fuel mileage. To let you now that the system is armed and working there is a green ECO displayed in the middle of the dash. I find the light annoying so I keep the ECO switch off.
We filled up with gas tonight for the first time since we tested the lower limits of the gas tank and we had been 477.6 miles of mostly just to and from work commuting. The Purple Whale drank 15.26 gallon of regular fuel, so we averaged 31.3 MPG for this tank.
I wonder what would happen if I left that switch on?