In this thread HankChief proposed a "Soderberg number" to be defined as the number of days travelled by bike / number of days travelling by motorised means.
Soderberg being the name of the cafe formerly known as Peter's Yard.
He included a link to this blog which is by a person who didn't allow themselves to travel by car at all (neither as driver nor passenger) for a year.
Now while I keep wondering if I cycle further then I personally drive a car during the average year, I've never done the stats to find out, and I'm certain that I travel further by car than I do by bike (my hillwalking habit sees to that).*
I've a friend who is trying to never buy stuff that has plastic packaging. She was struggling to buy cheese IIRC... I wonder how she does for shampoo?
*Yes, there are hills that can be done by public transport, and I've done some like that. But one of the things about being a member of a mountaineering club is the car sharing; if I stopped doing that I wouldn't really be a participating member of the club any more, and I haven't got to that point yet.