Here in Philly, my car has an average speed of 13.7mph. My average on the bike is just under 15mph. The morning commute is "reverse", in that most traffic is coming into the city and I'm heading in the opposite direction, so by car it is twice as fast as by bike. The evening commute home is ALWAYS slow, and now that Rte. 1 has a detour due to crumbling infrastructure 300ft above the Schuylkill River, it's even slower. My car commute home lately has been easily over an hour, while the bike ride reliably takes 47 minutes. The total commute time between the two on the best of days is 1.5 hours, but I always get home sooner if I'm riding the bike, and after 8 hours of work, it's necessary to clear my head.