[Shaun @ Tru6]

Nick, you were right, at least in the grand scheme of things. First, the 2500 psi washer was weaker than I thought it would be. No reason to believe the unit (Karcher) was defective, I just thought 2500 psi was stronger. Should have gotten the 3500 for the front wheel wells.

The washer completely failed on the aftermarket tar on the driver side but did a decent job on the passenger (it was lighter) and did a really good job on the rest of the tub. I ended up "painting" the heaviest/thickest tar with a mapp torch and hitting it with a plastic scraper and brass bristle brush. That worked pretty well. Was careful to move the torch around so as not to disturb the factory coating. Then I hit the area with gas and a super scouring pad. That got it down pretty clean, the gas dissolved the tar slowly but effectively. Then the washer to clean up and then wiped down with brake cleaner and a towel. Honestly not that much work and I'm not even sure how well a heated pressure washer would have worked on the tar. But I am sure it would have worked better than the cold water.