I have used the Gtechniq W5 Citrus All Purpose Cleaner for years, and currently only have this in the (APC) all-purpose cleaner category.  I have enjoyed using other high-quality products, though this is my preference.  I do not use products like these as much as the average detailer, as I lean on dedicated products.  I am also extremely discerning about the kind of products, particularly APC, that I use.  My focus starts on product safety of vehicles, followed by cleaning power, and later the cost.  Not the other way around.  I found this to be the best in safety category, and very good in all others.

You can use the product full strength or dilute 1 to 8.

A recent wash on a car that has been sitting for two years provided an opportunity to showcase this product as a pre-wash tool.  This bottle is diluted 1 parts W5 to 4 parts distilled water.

This car still needs some detailing done for a variety of other reasons, but I was surprised how easily 2 years of grime came off.  Much of the grime had broken down before a contact (wash mitt) wash, just from spraying Gtechniq W5 followed by (1 to 2 minutes later) foaming with Gyeon Foam and rinsing 3 to 4 minutes afterwards.

I also often use this product in conjunction with car soap for wheels, regardless of whether I use an iron remover for the break dust.  I prefer Gyeon Tire for tire cleaning.  But as a back or second option, Gtechniq W5 is my choice.  Often, I will clean tires twice.  My first will be W5 and follow up with Gyeon Tire.

Gtechniq W5