I am facing issues with my Passo lately. The car seems very heavy....doesn't change gear (automatically) as smoothy as it should. Between 40-60 Km/h, acceleration almost goes to 0....regardless of how hard you press the accelerator. Speedometer climbs really slowly until it crosses 60 km/h mark after that acceleration comes to normal.

Car jerks heavily when shifting from between N, R and D. While driving if I press the accelerator a bit too heavily.....the car produces a whooooooom sound, without any marked increase in speed.

I would like to know if this is an issue regarding the Transmission or the Engine? I am going to a mechanic this weekend....so need to know what to expect. Don't want to be taken for a ride by the mechanic.

Any pro advice would be highly appreciated...Thanks guys.