The first real jerk on the leash occurred during the oil crisis of the 70's. Now we have more fuel efficient cars. Awareness of what cars were doing to our air prompted cleaner cars. Gruesome statistics for highway deaths prompted safer cars. While these are impressive technological achievements, what may be the greatest problem posed by cars is physical size.
Most trips are by one person and less than five miles.
There simply isn't the space on the planet, nor the energy source required for everybody on the earth to have a personal car. Paradoxically, the car was what made the exodus from our cities to the suburbs possible, and the very same car brought the sprawl that has made the suburbs urban themselves. Building more roads and better cars has a lot of appeal until you realize that as soon as new and better roads are built new development quickly arrives. These days the car defines our how are cities are built. In the US, roads, parking lots and other areas dedicated to cars occupy half of urban space.