Since about 60,000 km - there is a gap of seconds between pressing the gas pedal and getting the actual acceleration. When I press the gas pedal there is a hesitation and when the downshift happens, it is very harsh. Then of course the car has a sudden "knocking" acceleration that panic's my passengers.

This is not safe. I have had the car for 4 years. It was working find at the beginning. But ever since it reached about 60,000 km, I have brought it in several times to the dealer trying to explain the weird behavior of the transmission. They took the car out for a couple road tests but never have experienced the harsh downshifting I claim. As a matter fact, the harsh shifting only happens when the car has been running for a long period of time (more than one hour). And the delayed harsh shifting happens when I press the accelerator to pass or when the automatic transmission tries to downshift to go up a hill (it is always between the 4th and 3rd speed). I inquired so many times at the service department but never got results.

I am kind of tired of complaining and anyway the car is still drivable. I just feel this is definitely a defect and I sure had hoped they would have found the problem and fix it before my warranty recently expired...