Frank, my A5 Tiptronic is quite responsive from a stop position, and I do not get that thump you were describing. However, I have noticed that it either will be really quick off the line or will gradually take off depending upon the amount of pressure I put on the gas. If I apply very light pressure, I think it does hesitate a little bit before the torque really kicks in. I only have about 800 miles on my car, so I'm still adjusting somewhat. You might want to have the dealer check things out regarding that thump. Doesn't sound normal to me.