which was produced by Transport for London (I believe) illustrates how cars are a wasteful use of real estate.
As you can see, 60 people in 60 cars (60 cars * roughly 10 foot wide lanes * roughly 30 foot lengthwise spacing) =
18000 square feet
60 people in 1 bus = (roughly 10 foot wide lanes * roughly 70 foot lengthwise spacing [this is generous]) = 700 square feet.
60 people on bikes = (60 bikes * roughly 4 foot wide lanes * roughly 8 foot lengthwise spacing = 1920 square feet
The area ratio of auto:bicycles is roughly 10:1 and for buses is roughly 25:1. And this is very very conservative. I haven't even incorporated the fact that automobile infrastructure in the USA is generally very spacious (wide shoulders, turn radiuses, parking spaces, etc.) so the real ratios are somewhere north of 50:1 - or even 200:1.
Back in the 1950's when America was a vast, unpopulated land, the relative cost to society of allocating swaths of land (roughly 10-20% of most metropolitan areas) to the use of automobiles did not seem like a waste. But with explosive population growth, the relative value of land has shot up, and thus the relative opportunity cost of automobile infrastructure has also shot up.
We need to explore using our transportation real estate more efficiently and more effectively. A combination of car-sharing, bicycle infrastructure, public transit, and walking will help us cope with the increasing population, both in absolute numbers and in density. Plus it'll have various health, quality of life, and sanity benefits for the population as you've already outlined.
Oh, and for further context, one last thing.
The average parking space takes up about 350 square feet of room, whether in a parking structure or in a surface lot.
On average, there are about 3-4 parking spaces per automobile in most American cities.
Therefore, for every automobile on the road, we must build about 1200 Square Feet of parking lots.
The average American dwelling is about 900 Square Feet in size.