I use #00 all the time. I really like it. It has a ton of lubrication and not a lot of suds, as said. I use 1 1/2 capfuls for about 1 1/2 - 2 gallons of water (a 2 1/2 gallon bucket). I really like it. It feels incredibly mild and is great for someone who washes their car a lot. I think it must be about the most gentle thing on your wax save water alone. However, if your car is really gross or you have a lot of bugs and crap, you might want to save the #00 for the next time. I usually use the Blackfire shampoo when I have some bugs to deal with.
I guess it depends on what you want out of a soap. I just want very gentle, safe cleaning. The super slickness of #00 gives me a lot of confidence in it. I really don't care about suds, and they can make it tougher to see if you got the crud out of your wash mitt, or to see how cruddy the water is getting. I also don't want a lot of gloss from it because it feels like something got left behind on your paint (which I guess it did). Who knows what it does for you protection, and how it interacts if you want to apply another layer... I always follow up a wash with a QD session just to make sure there are no little water spots. So I pick a QD (or don't QD) based on what I will do next. My car wash really doesn't need to add gloss or slickness.
How much did it cost you? It costs me about the same as a 16 oz of Gold Class car wash, about $5. Of course, you can easily buy 4-8 times that much Gold Class for like another dollar or three.