How could a remove oil from the trunk carpeting of a car?

Some time ago, over a year, I changed my oil and put the used oil back into a oil jug. This then sat the the trunk of my car for... well a long while. Over time it leaked and there is oil in the carpeting. A few towels and one large winter jacket have soaked up a lot of it by sitting back there. But I want to be able to clean it properly. I figured I could buy the a bag of oil spill cleaner, its like cat litter, but I didnt know if that would work if I just put it back there. Its not a giant area that needs to be cleaned. Should I get some cat litter, some oil spill kit, something else?