The Smart has some really good
sound proofing on the carpets but when it comes to the doors, boot
and other panels it is non existent.
Aftermarket sound proofing is
available from companies like dynamat and fatmat, its pricey stuff
buy what a difference it makes in drowning out the noises from other
cars or keeping the sound from our speakers in.
First things first, remove
the panel or piece of trim you wish to apply the proofing to, clean
the surface with a good de-greaser, cut the proofing to size and
apply it with a roller.
The draw back in sound
proofing is that its very heavy, so if you want a high speed
dragster then this isn't the mod for you.
(Pictured below are the doors
with fatmat applied to them.)