Occasionally on starting my 05 XJR I get a subtle "thump" sound simultaneous to the engine firing up. The car is normal and perfect in all other respects. Engine mounts come to mind.

Any ideas? The sound is from the front/engine compartment for sure and occurs about 50% of the time hot or cold.

 

Bump, thump, as it were. Anybody?

 

Mine does this and I pretty much decided it was the transmission pressuring up.

 

I'm glad this isn't exclusive to my car anyway. Thanks for the response.