The energy saved by replacing a 100-watt incandescent bulb with an equivalent compact fluorescent bulb over its lifetime is sufficient to drive a Toyota Prius hybrid car from New York to San Francisco." Lester Brown, "Plan B 3.0" pg 215, Norton, 2008.
"If every American home replaced just one light bulb with an ENERGY STAR qualified bulb, we would save enough energy to light more than 3 million homes for a year, more the $600 million in annual energy costs, and prevent greenhouse gases equivalent to the emissions of more that 800,000 cars." www.energystar.gov