I used it in my '55 Ford Ranchwagon and it works great.
I did not use it in my '30 Town Sedan. Even tho my TS is not a 'Points Car' I felt it was too permanent. That stuff REALLY sticks down.
In the TS I used the foil covered batting type, just laid it under my carpet. Not as good as the Dynamat but I sorta enjoy my Town Sedan's 'sounds' as I'm driving down the road...