While browsing another site, I read a recommendation to scrub the mats before you do the initial vacuuming. It was stated that this was an important step for initial dirt removal. 
This is totally backward from the way I have done it for years and I don't really think that is good information, but I'm certainly ready to learn what the benefits might be.
My process:
1. Dry vacuum. In the winter months, I will sometimes blow the road sand out with compressed air before vacuuming.
2. Spray with an APC, let it set for a few minutes, brush thoroughly, let dry and vacuum again. Tar or grease stains are removed with a tar remover after vacuuming and prior to spraying with the APC
or
2a. Wet the mats with the hose and srub them with a mixture of Dawn & water using a brush, then rinse them until the soap solution is gone. This is rarely needed or done.
The scrubbing prior to vacuuming seems like it would turn the dirt in the mats to mud. That's the reason I try to vacuum as much dirt out of the mat as I can before I scrub.
What are some opinions of others?
Charles

This is totally backward from the way I have done it for years and I don't really think that is good information, but I'm certainly ready to learn what the benefits might be.
My process:
1. Dry vacuum. In the winter months, I will sometimes blow the road sand out with compressed air before vacuuming.
2. Spray with an APC, let it set for a few minutes, brush thoroughly, let dry and vacuum again. Tar or grease stains are removed with a tar remover after vacuuming and prior to spraying with the APC
or
2a. Wet the mats with the hose and srub them with a mixture of Dawn & water using a brush, then rinse them until the soap solution is gone. This is rarely needed or done.
The scrubbing prior to vacuuming seems like it would turn the dirt in the mats to mud. That's the reason I try to vacuum as much dirt out of the mat as I can before I scrub.
What are some opinions of others?
Charles