Boy, that poor little thing had been sadly neglected.
Looks like it needed some real love and you are just the guy to do it.

You are actually really lucky that you have a black top.
Mine was white, and it was a mistake. But, live and learn!

I found a couple of things that worked really well for me.
One was Simple Green and a soft brush. Hated the smell so I switched to
Greased Lightening and it worked like a champ too, with a soft brush BUT
with either, they will strip your wax.  And on that little black trim strip
around the back ot the top by the deck lid, it will get spots from the
cleaners removing whatever has accumulated on it.

You can probabaly figure how I know this.

SOmething I tried, in my efforts to keep my top looking good was those Mr
Clean Magic Eraser pads. Little white things that look like sponges but you
use only with water. They work like a million bucks! Good on bugs too in the
front and get specks off of your stove top. So, for the last little while I
was using those to get the hard stuff and car wash (Meguiars) and a bristle
brush. Because yours is black, you may be able to use a vinyl treatment
(Meguiars again has some good stuff) on it to make it look all pretty again.
Experiment, you can always wash it off!

*hee hee* "Liberty Girl."

Yea, I have been trying to think of a new nick but man it's HARD!