We're loving our 2007 RX 350 which we purchased a few months ago. One thing that baffles me, though, is that as quiet as the ride is, if we go over say some tiny bits of gravel on the road where some road work was done, perhaps, or anything where there is the slightest debris on the road, it sounds really loud under the car. For instance, this morning, I forgot about it, was driving to work, and hit a small patch of I guess you could say somewhat powdered gravel on the road. As soon as I did, I thought something busted open in the back seat, but then remembered the deal with this car (mine, at least).

So the first question is: why is it so loud in these cars? And my second question is: is there any cheap fix for this sort of thing? Any sort of material or something I could use to block the sound without messing up the car?

Thanks for any suggestions