for about three miles on the highway. Is this a sign of low tranny fluid? I tried to check that but the designers of this car made that kinda hard to do.
When it is cold,say below 40, the transmission will not shift into overdrive on 2007 Chevrolet Malibu
Is the engine reaching proper operating temp. before you are on the highway? Normally cars won't go into overdrive until warmed up past a specific temp. , If your thermostat is opening to soon causing an extended warm-up , that may be delaying the shift. Maybe it would also be good to have the fluid level checked, by a shop , if needed.