best thing that worked for me (i'm a smoker) was to windex the fabric on the seats and stuff. i used the windex with vinegar, and not only does it get the tar stains out, its easy and it should clear up the smell. just spray some on, let it sit for a couple of seconds, then scrub with a paper towel. seriously works wonders. plus its cheaper than getting your carpet cleaned (it works on really old stains too, i had coffee stains by my cup holder that were more than a year old, and i got them out with barely any scrubbing).