What? I live in the outskirts (zone 6) and absolutely would not want to drive to Oxford Street. Quicker to take the train and much less stressful. We used to live more centrally and most people didn't own cars, or (like us) used them to go out of London rather than more into London.
I'm with the PP who said I'd rather pedestrianise it, than add more cars!
The reasons I don't go to Oxford Street are - it's too busy, too noisy, i prefer my own local high street / shopping centre. And yes, nowadays I can shop online too.
What might tempt me to go - taking my preteen daughter as an experience (and having it pedestrianised would be a bonus for that), or a particular event on.