I put Simple Green industrial (it's purple in color) in a spray bottle and got the carpet pretty soaked. Waited about 10 minutes for it to soak in.

Then used a cheap upholstery hot water vac with only hot water in it (no other cleaning chemicals) and cleaned it normally. Looks like new. The water was the blackest I've ever seen.

Then I got a ozone generator for about $80 (Enerzen 3500mg) and ran it with a window cracked for two cycles. The funky old car smell is almost gone. I have the ozone generator running in my house now (no pets) just to freshen the place up.