Most environmental action involves reformulating a problem by reconsidering the needs that gave rise to the polluting solution, and finding a non-polluting one. One example is to say our need isn't to drive to the supermarket and do some shopping, but to somehow obtain food and household supplies. All transport involves environmental impact, even clean transport requires energy consumption and has spatial effects, therefore wherever transport can be minimised or displaced doing so makes the overall system more sustainable.
Transport displacement is environmentally, socially and economically optimal. Cars aren't needed to deliver goods, and a dedicated delivery van creates less traffic and uses fuel more efficiently than individual vehicle journeys. From local stores such delivery can be quicker and more accountable because of proximity. Shopping can be done via an Internet or telephone order that is delivered by the retailer's van, thus saving a lot of fuel, roadspace, collisions, a parking lot, some of the customer's time, some space in the supermarket etc. which not only saves environment but money, and the goods could be cheaper, even with the new costs of information technology and service personnel. Thus it's not a matter of deprivation but means finding ways of satisfying economic or social needs, allowing goods and people to circulate without resort to major movement of vehicles.
A car ban would aid the development of medium density living with the minimization of interspace. Reductions in traffic, liberating space, make it possible for things to be closer together so transport is also reduced in distances, not just in mode. The progress of telecommunications make this possible and, in the context of a car ban, a virtuous circle emerges where the infill proximity of goods, services and socialising venues reduces transport impacts by carting things and people shorter distances. Higher densities can also mean, if property prices can be controlled, cheaper goods because of better turnover. Liberating all parking and much roadspace would dampen property prices for some time.
People fear isolation in a "virtual world", and this currently does happen: but though it uses telecommunications and the Internet, transport displacement does not involve isolating people rigid in their homes locked to computer screens with only virtual relationships, rather it makes the local outdoor environment safer, quieter, cleaner and less dispersed, in short more walker friendly, allowing local shopping, recreation and socialising venues to be within walking distance of all homes within the urban area (more 1).
Communication and computers can also displace some work commuting, in much banking, clerical work, etc. Much development of both technology, access and managerial attitude need occur before telecommuting becomes a major work mode, but it is perfectly feasible. Also, because so much time is currently wasted each day in commuting and transport foul-ups, leisure time can be increased without reducing productivity; if one includes the hours worked just to fund the car system, this saving could become the equivalent of a four day working week. And for those who still had to physically commute, the time would be radically reduced by public transport geared for quick journeys in a low traffic environment.