Please bring it back clean and ready for use by the next renter. The car has an unlimited car wash pass with SuperAmerica, so you can use that at your convenience (and there are two different SAs nearby the vehicle's location). If you get the car dirty and do not have time to take it through the car wash for free, you will be charged a $15 cleaning fee.
Refuel with premium gas, and post a pic of the receipt to the trip photos or leave the receipt in the glove box. If you forget to refill the tank, not a problem - you'll be charged for the price of the gas plus a $15 convenience fee.
And don't forget to have fun!