Should city centers go car-free?

Our city centre went car-free on weekends two years ago and the thing nobody predicted happened: the shops that said they'd die are busier. People walk slower past a window than they drive. I know that's one city and I know the buses have to actually work. I also know that every time this comes up the first reply is about a delivery van and the second is about someone's grandmother, and both of those are real and neither of them is a reason to keep forty thousand cars idling in a square built for horses. So I'll ask it straight: should city centres go car-free? I say yes, with exceptions you can count on one hand.