One way to influence politics is to spread the culture of being habitually green. The big gains may all be political or require extensive city design, but changing the mindset to 'people want green; and superficial won't cut it' is a big part of making that happen.

Do I want to give up my car? No. What if I did want to; how would that change my outlook? I'd want cities and a job that accommodates those desires. What if everyone wanted to? Those cities would be built and politics might make cars more restricted.