The problem is that all the infrastructure that cars need (roads, parking lots) makes everything WAY further apart. For example, downtown Houston is literally like 25% parking lots by area. And that's not even counting other car infrastructure like roads. So to some degree, cars are just satisfying a demand for transportation that they themselves create

Denser, less car-centric areas are more economically productive than less dense areas. Car infrastructure prevents density. So I would argue that, at least in some cases, cars decrease economic efficiency

Put simply: The existence of motor vehicles is good, from most perspectives. It's fairly hard to argue they're not.

The development of cities caused by unrestricted, broad private car ownership without lots of careful coordination on that development, is in the reverse situation: it's fairly hard to argue it's net-beneficial, because it's so incredibly expensive in all-told money, time(!), liberty(!!), and, if we'll allow consideration of such things in a basically-economic analysis, pleasantness of environments for humans to exist in.