I got a grout sponge Friday at HD and tried it yesterday and I think I'm in love thanks to the cheap price tag. I used it on my black Bonneville yesterday and saw no difference in performance from my sheepskin or Schmitt. I love it because, like the Schmitt, it holds so much more solution. I hate it using the sheepskin and having half the solution hit the ground before the paint. It worked great to squeeze it some to get some solution on the panel, clean an area, then squeeze it more in another area, flip it over and clean. One thing that never impressed me about my sheepskin is that no matter what, I always find particles in the hairs. But I couldn't find any with the sponge. I would clean it in the rinse bucket, and it came out perfect. Even after it got black a couple times from the areas behind the wheels, it came clean. I'm assuming the particles of dirt just go into the pores of the sponge when washing. I actually have had one of these sponges for a couple years that I used on grout, but it's the one with the coarse white backing. I thought about trying it, but it's too ratty looking. I actually am going to pick up one of those the next time I'm at HD. It should work great for cleaning the tar and crap on the wheel wells.