I'm sorry if this seems a little (or more than a little) scatterbrained.

Not at all; it's excellent.

I'm utterly convinced that we inhabitants of the USA must -- must -- cut down on driving, right away, immediately, now... and it's far too late for voluntary measures.

We need either gasoline rationing, or heavy gasoline taxes above some level of usage per person (with negotiable ration coupons, I think), or... well, write down your best idea on how to limit private driving.

We need subsidized public transportation, plausibly supported by gasoline taxes, especially short-distance intra-urban vehicles such as jitneys or small buses. These should pervade the urban area so that no one has to walk more than two or three blocks from home to get into a jitney. Some of the jitneys should deliver people directly to their destinations rather than running over a fixed route. Computer routing, recalculated whenever a new passenger states a destination or a new pickup comes in from the dispatcher, should greatly help to speed the trips. Live traffic reports must be funneled into the routing system (this feature is not optional, and will require new, funded traffic reporting).

And that is just the beginning. Next come mandatory measures pertaining to winter heating in cold climates, airline transportation, railroad shipping instead of trucking where possible, and... well, you get the idea. It's way past time to get serious about all this.