I had a late night flight out of Seattle to San Francisco on Sunday night. Freezing fog conditions made for an even later departure, though. Our scheduled departure was pushed back so much that it was 1.15 am by the time I picked up the rental car at San Francisco airport. Luckily the little ‘air train’ out to Hertz still runs at that time, and the rental car facility operates around the clock. And hey : there is almost no traffic on the Bay Bridge in the dead of night.