Bang/Clunk/Kick - after giving gas from a rolling stop - Feels like just got hit!

[E53fan16]

What's up fellas. So I'm back in the thread. The prior X5 4.4i that I was looking into I did not get it. The dealer was not forthcoming about the oil leak and just seemed uninterested in selling the vehicle to me since I was asking so much knowledgeable questions.

Since then I continued to search for a 3.0, but the pickings in NYC have been slim, and most that I have encountered with decent miles have been in horrible condition.

While searching on Saturday, I came across a black 2006 4.4i with 79K in miles. Yesterday, I drove out to the dealership to have a look at it. The exterior condition was pretty good, it has some scratches. The truffle brown interior was mint.

So while driving I did notice a slight hesitation upon acceleration from stop to stop light, but then again most BMW have a slight hesitation. It felt as though I really had to lean into the throttle to get it going. Coming to a stop I noticed that shifts were not smooth and a bit of lurching was observed. Highway driving the shifts were very smooth. I alerted the salesman about the hesitation and he informed me that the truck has been sitting for a couple of weeks, so that could be the catalyst. I told him to come around and drive it. While he was driving it I did not get a sense of hesitation because he was really pushing the hell out of it. He said "the 4.4i is not a RX350 so don't pussy foot the throttle, drive it like how a BMW is meant to be driven". Upon him leaving one stop light under full throttle, I did notice a slight kick in the back or bang feeling. He felt it too, but he quickly said that was his fault when he went from the brake to the gas abruptly. Not sure what he was talking about, or it was just him giving me bs.

I did not notice any leaks or white smoke while the vehicle was idling. I had the sales guy give it a couple of revs and no white smoke. However, would the white smoke probably be more noticeable on a cold start? I was not there for the cold start as they had took the vehicle to wash it once they knew I was coming to see it.

The car fax shows both axles were replaced, should that be a concern?

Other than the hesitation and questionable transmission shift the vehicle seems good.

I'm debating looking for a indy mechanic to do a PPI on the vehicle.