Demand for Hybrid Vehicles

There is a strong debate going on over what could be a realistic expectation of hybrid vehicle sales in the next few years.
Here is an optimistic projections:

"Demand for fuel-saving hybrids could grow to as much as 10 percent of total U.S. new vehicle sales by 2010", Jim Press, Toyota's U.S. managing director, said last month.

We have seen similar optimistic projections earlier. A more pessimistic projection from J.D. Power was about 3% market share by 2010. The JD Power report talked about the hybrids "reaching a plateau" at about 3%, which I find quite difficult to accept as opposed to hybrids just hitting 3% sales in 2010 with a potential to grow in the future.