Vettel was second in practice and he needs just fourth place to secure the title.
"It was alright today, it was very slippery for everyone. It was quite hot today and in terms of track conditions not that easy, so I think everyone suffered the same kind of problems looking for traction and stability etc", he said.
"So far we can be happy, we have to do our homework now, first comes tomorrow morning and we go from there".
Team mate Mark Webber was third in both sessions.
"The track was slippery today, it's very hot. I think we're all a little bit surprised by the lack of grip we had, but we got what we could out of today in these conditions. We got through plenty of stuff and also did a bit of’13 work, which was useful. It’s the last test before next year, so we made the most of the beautiful sunny day in Brazil, before we go to colder Jerez in February".