I recently financed a 2001 Volkswagen Passat V6, and am getting not very good gas milage. It looks like the gas is just sucking away. I've been using just regular unleaded gas, should I use another octane? Or could it be something internal. The car runs reat, but gas sucks. I don't know much about cars, and could use some positive help to let me know what my next step should be. Thank you.