Well, after clay bar, Ultimate Compound and two coats of NXT 2.0 wax - I can honestly say the car looks as good as the day I brought it home. The dealer had detailed it and done SUCH a good job that they felt comfortable tacking $300 on for "dealer prep" (dealer prep of a USED vehicle???)

Now, they also steam cleaned under the hood - but we wont be bathing the electronics under the hood with steam, that is for sure.

Anyway, I now understand the use of, and belief in, the Clay Bar.