While I have both Prestone foaming carpet & upholstery cleaner and Blue Coral Dri-Clean carpet & upholstery cleaner, I find myself using the Meguiar's APC+ instead. It is awfully handy to have one product to do carpet, upholstery, vinyl, wheelwells and tires. As I have said before, I like easy.
Since my carpets aren't usually in too bad of shape, I might not be the best test available. Anyway, the APC+ seems to do a good job. (As did the Prestone and the Blue Coral)
The cleaning products are used after a good vacuuming with my Metro Vac-N-Blo vacuum cleaner. This thing will lift the carpet mats right out of the vehicles. One powerful vacuum cleaner. I also use the discharge or blower side to aid in drying after using the APC+.
Charles