Hi Kenny,
You have 2 excellent products for cleaning a grungy commercial carpet... Encap-Punch & Encap-Clean DS2.
In fact this photo was shot from behind the customer counter at a new car dealership. As you can see, the Cimex/Releasit combo knocked the ball out of the park!
Here is what I would recommend:
Mix your Encap-Punch at its strongest dilution (12 oz per gal). Spray the carpet liberally. Allow about 5 minutes of dwell time.
Mix Encap-Clean DS2 at 4 oz per gallon. Use the hottest water you can get (a
bucket heater is a nice accessory for getting piping hot water).
Scrub the carpet making 1 wet pass, followed by 2 mostly dry passes. Take your time on the dry passes. Agitation is king here. I would also suggest using FiberPlus Max pads - since they add some extra scrubbing punch.
Be prepared to be impressed with the results :-)