Driving, including walking to my street-parked car ~2-4 blocks from my apartment, inching through horrific traffic, having to wait to park in a lot downtown, then having to find another parking spot near my apartment: ~70 minutes round trip on a good day (if there is such a thing, when being forced to drive in SF). Biking: ~20 minutes to work, ~25 home. So my ratio is somewhere around 0.65 I've driven to work a grand total of two times in the 14 months I've worked downtown. Both times were terrible.