Even just the manufacturing of tens of millions of vehicles a year is tremendously energy intensive considering the extraction of raw materials and refining them to, ultimately, vehicle disposal. Then there is the space consumed by vehicles when they are parked or on the move (or not). With the average car carrying just 1.5 people, the amount of material and space required on the road get from point A to point B is hugely disproportionate.
Suzuki believes (again, correctly) that we need to reconsider our entire dependence on personal transportation, especially in urban environments with a large population density. Improvements to and increased use of mass transit would go a long way to addressing the issues of congestion, but there are other alternatives as well. While Suzuki doesn't specifically mention them, automakers like General Motors are researching the future of transportation with vehicles like the EN-V concepts and some MIT students envisioned the stacking car a few years ago. Such vehicles – and car-sharing programs like Zipcar – could minimize the physical footprint of transportation while retaining the flexibility afforded by keeping it personal. Whatever ultimately happens, the status quo is definitely unsustainable.