There are cans/tins of sound deadener you can buy from places like Auto One or Bunnings, its like a thick tar, and you brush it onto the underside of the car. I spoke to someone recently who does a lot of highway travel in a Hyundai Getz, and they said it makes a noticeable difference. I was thinking of trying it on my CL9.

I think tyre noise is the noise I want to block out most. Its expensive, but i've been wondering if using it in well targeted areas like the interior side of the wheels arches will make a notable difference. Putting Dynamat in doors will improve stereo sound and rattles im sure, but not too sure how much exterior road noise it will really block out.

Either way please report any findings, I'll be interested to know.

Ollie