If you live in SF, its much more more convinient to hop to a zipcar/getaround car block away from your house for a day trip to Napa, than first go the airport/d

If you live in SF, its much more more convinient to hop to a zipcar/getaround car block away from your house for a day trip to Napa, than first go the airport/downtown, where it takes additional 30-60mins to do the whole travel+process+traffic. Plus you have to do it on the way back and fill the tank (zipcar gas and tolls are free). Also the SF rental shops usually close after 6/8pm so you cannot drop the car off after that.