Mequiars is very good. I've had good experience with the gallon jugs if carwash soap I get at Costco periodically. I just checked the current batch I'm using... it's Turtle Wax brand! LOL. I haven't noticed any problem with it cleaning the cars well, though. Maybe your water is a bit hard? Or perhaps the paint is worn out from just washing and not getting the rest of the paint care treatment?
It's very important not only to wash the car but also to polish it and then wax it. There are combination cleaner/polish/wax products, but they work about as well as shampoo with conditioner in it does for hair.
In general, you want to use three steps to clean an automotive finish: a good cleaner to remove dirt, then a good polish. Mequire's #7 is good for that. The polish takes out small imperfections in the finish and also nourishes the paint with oils. After the polish, then a wax will seal in the oils and help to protect the finish. There are a variety of grades of polishes to handle various degrees of finish deterioration. For really poor finishes, they might need to be buffed out with a mechanical orbital buffer. But these take some practice to use properly, and it's very easy to burn a hole in the paint with one if you're not careful. These are different than the random orbital "car polishers" you can buy just about naywhere - those are simply an extention of hand polishing, and don't generate the heat needed by the more aggressive polishes to do the job properly.
Mequires has a Gold line that is specifically for hand washing/polishing/waxing. Coral also makes good products, I think.
For rims there are good products on the market that help to remove brake dust. For tires, there are also good products that also impart a glossy sheen to the black rubber.
