Mild Thump Under Right Foot
 

Often, while gently pulling away from a stop, and typically right after I’ve started driving, I feel and hear a double “thump.” The feel is pretty mild, but you wouldn’t miss it. Kind of like a light tap with a mallet. It usually feels like it is right under the accelerator, but always somewhere under the area covered by the floor mat, let’s say.

With that lousy description, any guesses what I’m hearing and feeling? I’m thinking it is something engaging, or disengaging, but that’s a guess. Any insights are welcome.

It's normal. It has to do with the ABS. It occurs at 25 MPH each time you start the car.

Thanks. I glanced at the speedometer this morning when I felt it and it was right at 25 MPH.

Noticeable by almost every owner of the new generation A4 on the first pull away from the dealer's lot. We bought ours when they first hit the dealer showrooms. Many staff didn't know what it was but was "probably" normal. Some said they heard it was nothing to worry about but that a tech services bulletin would be forthcoming. Most recently I've been told it's a proper pre-positioning of the brake calipers.

It doesn't happen in my two day old RS3, FWIW.

I've been wondering about this too - I'll have to check the speedometer the next time I drive.

It's the ABS check. Completely normal.

My B8 A4 does exactly the same thing.

What exactly is it checking though and why don't other cars check it?

My Honda did it at 10 mph.