One week down. I started my car for the first time in over a week last night, took my son to scouts in town, a 10 mile round-trip. Besides commuting daily, I also thought up that if I can drive my car less in a month than I cycle in a week (100 miles) that'll be cool too.
I've been posting combined bike+car mileage stats of > 200 MPG to my livejournal, mainly to tweak my Prius-owning friends and their 60 MPG tales.