Consumerism is the societal condition where every individual wants and needs to possess an individual unit of any object or device that they may want or need to utilize, where these objects are mass-produced by an economy biased toward new production and against maintenance, reuse or service. So goods are made for use and disposal primarily after one owner and durable goods spend most of their existence inactive or stored. Of course a world with derisory public transport and car infrastructure individuates transport in archetypical consumerist fashion.
Its symbiotic bondage to consumerism is why capitalism is unlikely to be sustainable or save the environment. The classic American model of becoming wealthy is explicitly consumerist (more 1). All production, no matter how "clean and green" will create some pollution in resource acquisition, production, distribution, use and disposal (more2) and consumerism's whole purpose is to proliferate production. So even with the improvements to production processes that can vastly improve the per unit pollution of production, consumerism maintains pollution levels by producing more of the things and the world's environmental indicators keep getting worse. Only a conserver economy, more based in services than manufacturing to extend the life of each object and minimize garbage, can bring down pollution, and it requires different distribution to maximise the users of each produced object. The only hope within capitalism lies in the expanding service and rental base, and these need to reduce in price for more universal uptake.
Cars generate consumerism by:
The more fragmented society becomes into isolated individuals, the more demand exists for consumer goods (as each person must own their own) (more 4) (more 5). The car is the flagship of consumerism, it's the biggest single consumer good, if you want to move around as quickly and safely as others you must consume a tonne of metal, and because roads break up human settlements, increasing all interspace distances by 50% or more and making local circulation dangerous and unpleasant with traffic, their hegemony ensures the maintenance and worsening of consumerism.
Banning cars would increase outdoor life and bring increased local human interactions between dwelling frontages and passing walkers, cyclists etc. This increases opportunities for ordinary redistribution of surplus goods and services, in the form of borrowing, pooling, swap, private trade, and handing on objects no longer useful to the owner (more 6). These interactions are one of the pillars of satisfactory social relationships and community, (more 7) relieving some income and security stress while also reducing pollution, consumerism, and transport; with major ecological benefits.