Practically, no.
I live in London so I do a fair bit of walking and tubing/bussing also.
But I often need to lug heavy things around, and fairly often travel to places outside of London, and outside of easily trainable places.
If I just worked in one place and commuted on public transport, and my social life was all in London, yes I could do without a car fairly easily - I could just hire one when needed.
But the practical convenience of being able to just walk out of my door, get in the car and head off somewhere a couple of hours drive away without having to arse about with tube then train then taxi etc.... or waste time with hire car formalities, is too nice.
Giles..