I drive a 2014 Mercedes Benz CLA 250, which I bought in January, I find a gradually worsening problem with its transmission, with poor throttle response and lumpy and jerky shifts under some hard acceleration. When I showed it to the dealer the first time, they denied finding any problems, however, they seemed to have reset the transmission and it worked, but after a few hours of driving, it went back to being erratic. I, now, also hear and feel a light metallic clunk during downshifts and it has steadily gone worse in terms of throttle response, be it in the ECO mode or Manual mode, Sport mode is ok (probably, due to the high revs, I cant very easily distinguish poor response).
I have read in reviews that the car is lazy in ECO mode, but my car shows a distinct and noticeable lag in throttle response (0.3-0.5 sec) even from stop, same with reverse, it needs a little more than a push to the pedal to get into motion. I have complained about this to different dealers, but they all deny any problems and insist that the car is functioning as designed. I didnt have any problems for the first month after purchase, so I was very happy with its performance then.
How can I determine if this is really a problem in my car, please advise? FYI, the fuel economy seems OK (25-27 mixed driving), but I believe that is because I am very light footed with the accelerator now, as it doesn’t offer any fun, driving normally. I can provide more details of the problem if needed.