I'm feeling in the festive mood for this today -- this week we got rid of our second car, and now only have VW turbo diesel golf.  As my wife takes the car to work, I now have no choice but biking or walking . . . .  
Good move! Have you thought about biodiesel?
I have, and there are one or two places in Ottawa that sell biodiesel blend.  I checked out going to 100% vegatable oil, but I don't think that would be too good on the warantee.  Last I checked, Grease Car didn't recommend it for the new pump deuse engine. I coulda switched over my old 1982 Mercedes 300D, but the fuel efficiency was so crappy on those old diesels (10 L/100km)compared to the new ones (5-6 L/100km) that is wasn't worth keeping anymore.  Well, that and the rust problem that was starting to develop . . .
You're in Ottawa? Me too! (well, close to it, but I study at Ottawa University). Have you seen this: http://www.treehugger.com/files/2005/09/biofuel_filling.php (I write for Treehugger.com, btw, though I did not write that post)