Between Monday 2004-04-05 and Friday 2005-04-01 I cycled my 6.1 km commute 323 times, roller skated it 51 times, used public transport 33 times, ran 9 times and rode in a coworker's car 6 times. This sums up to 422 trips in 211 days. I haven't counted the time spent on business trips out of the city into any of these totals.
My commuting is thus 90.8% petrol unfriendly.