I once tried it too and quikly gave up.
1) There is an unbeareable polution made by the cars (especially the *green* buses). When making a physical effort , breathing this smoke is worse than sitting in the closed car doing nothing.
2) Many times I was close to death thanks to our good temper , nice and concerned drivers (again especially the bus drivers) who brutally ignored my existence/rights on the road.
3) The conditions of the roads are horrible too. Lots of holes and parking cars everywhere.

Conclusion,
Until I'll move to Amsterdam I'm not driving my bikes any more (except when I'm going to the park driving for fun).