Second time today I have heard a noise from the front of the car (I think) while cruising happily along in a straight line.

It sounded just like I hit something ... like three bumps, really quite loud!

The first time I figured that I just hit some wood or something, but this second time I pulled right over to check as in about 15 years driving I have never once not seen road debris that I have hit. There was nothing on the road what-so-ever ... I performed a very quick visual inspection under the car and in the engine bay but saw nothing untoward.

Any ideas ... this is a rather worrying noise for me!

How are your brakes? The last time I had noise which sounded like bumps, my front driver brakes pads came out. Found out for sure 20 miles later when all I had was metal on metal grinding sound and bad braking capability.