Comments about 3M 3M Marine Mildew Block 500 ML Marine Mildew Block:
I certainly liked it, easy to use. The spray leaves very thin film, and makes the vinyl shinier a bit.
On the con side, after the spray dried out on vinyl, you could see the marks where drops were.
After all, I might have not used it right...
The bottom line - it's easy to use, and it works.
It's been few weeks now, and the seats look like new.