Air Filter for Prius 2010 to 2015 - extend the life of your hybrid battery The cooling air intake is about 6 inches above the seat bench so a lot of dirt can get sucked in in when the fan is running. Plus the fan blows straight in to the bottom of the pack. About 1/4 of the dirt sucked in ends up in the cooling passages between the modules. YOU CAN PREVENT THIS WITH A FILTER THAT JUST NEEDS TO BE VACUUMED OCCASIONALLY!