I am not a fan of using Bleach White on anything on a car, since the product will remove the oils that make up the top vinyl, or the rubber of the tires. It is a very caustic product. I would suggest using Scrubby Bubbles and lots of water. Also, you can scrub the top with a natural bristle brush, but stay away from anything that is stiff. You want to lift the dirt out of the vinyl, and flush it away. Once the top is clean, I would use the Ragg Top dressing on it to seal the material. It is a great product, however, it is also quite expensive. You have an investment in the vehicle, so it is best to take care of that investment the best that you know how to. Also, keep in mind that soaps don't remove oils, but detergents do. That is why I don't use detergents on the cars, unless I want to strip the wax or oil from the surface.