I have used a number of things over the years, some of it depends on whether the top is a light color or dark color. But generally, I scrub it with Ford Triple Clean (I don't think you can get this from your Ford Dealer parts counter any more, I bought a case!). Or, Simple Green (half diluted is plenty strong) will do the trick as well. The important thing for me, especially with a lighter color vinyl top, was to scrub it with a soft bristle brush to loosen up all of the junk that adheres to it.