T.O.
I rent one about every 6mo. they do work well, depending on how dirty your carpet is depends on how long it takes. I go slower in the high traffic areas just to make sure I get all the dirt. My house is about 2200 sq ft and it takes me about 6 hrs with my kids home to clean the carpets, if they are at school I can get it done much quicker. I don't know about tar sorry.