I used 303 Fabric Guard and it worked great.
http://www.amazon.com/303-30606-Fabr...av_hcs_bia_t_1
I would not use a power washer on a fabric top, but I'm pretty anal about cleaning it. I also never use auto car washes. I hand wash and use a soft bristle (horse hair) brush to work up a lather and then rinse. I also use a lint roller after the top is dry to get any horse hairs or fuzzies that may have stuck around.