I think the issue with Back-to-Black might simply be that it's a little difficult to spread it evenly over such a broad area. Did you ask over at the Mothers forum at
www.waxforum.com? They're pretty helpful over there.
I'll presume we're talking vinyl. In what condition is the top? Maybe a good cleaning and something like Mothers Reflections Tire Care (which is also a good vinyl dressing) would do the trick -- it makes my BFG g-force Sports darker than when I use Mothers Protectant, and I like the way it looks.