I've noticed that while the weather is cold the clutches engage like a manual tranny until they get warm (I believe it's called clutch chatter). The "clutch chatter" or whatever it's called, happens on warm days when you start from 0mph with a moderate amount of gas. If driven like a granny or a lead foot the clutch transition from 0 to whatever, and from 1st gear to whatever gear is smooth (1st to 2nd or 1st to 3rd or 4th).
Periodically I change from auto mode to manual mode just to see what gear it's in. At 30mph it's in 4th gear and at 35mph it will change to 5th or will let you change to 5th gear. Depending on the speeds traveled while switch gears, it will downshift automatically.
Stock with factory Sony 10-speaker HD stereo and 4-wheel disc brakes.