This is the product you want. De-oil-it or de-grease-it. It's far better than anything else. It won't harm metal, fiberglass, aluminum, etc. You can degrease your driveway and wash it right into the street with out fear of the product or grease polluting the environment.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=http%3A%2F%2Fdeoilit.com%2F&ei=umQsVdyhBJWgyASJ2YDABw&usg=AFQjCNGIqWjgPXT7DhxN4UfKgazHEr6syA&sig2=ZaPNVruzqrsXo__8unajLA
A pressure washer will be ok on fiberglass. Put the soap hose in a bottle of bleach to brighten the hull. I am sure you know to use caution with the bleach you don't bleach any carpet or fabric. It won't harm the vinyl seats but I wouldn't hit those with the power washer.