The first person I heard talk about the car in the garage as a possible power source was Amory Lovins, shortly before or after the Atlantic Monthly article on the hypercar, about fifteen years ago. It's a useful concept to think about a parked car or truck as at least an auxiliary generator. In fact, there are some people who are doing it now. After the recent ice storm in Harvard, MA (not affiliated with the school of the same name), one Prius owner used his hybrid vehicle to provide back-up AC power. If you have Prius envy, there's now a kit on sale (at least in Denmark) to make every vehicle with wheels over 15" into a hybrid.
Of course, this idea isn't new. Edison and Ford teamed together on an effort to produce electric houses and vehicles with on-site gasoline and wind generators before WWI.
Update: Thanks for the Recommend. Must be a slow Sunday night.
From page 136 of Internal Combustion: How Corporations and Governments Addicted the World to Oil and Derailed the Alternatives by Edwin Black (NY: St Martin's Press, 2006 ISBN-13: 978-0-312-35907-2):
In the fall of 1912, the promise of Edison's new battery rose to the next level. His latest wizardry would allow every home, automobile, and industrial source to function as a freestanding generating station.
In mid-September 1912, Edison announced the result of some fifty thousand experiments conducted during seven painstaking years - a radical new energy-self-sufficient home. He called it the Twentieth Century Suburban Residence. ostentatiously overstuffed with every modern gadget and appliance from a coffee percolator to a washing machine, to room heaters and coolers, to phonographs and tiny movie projectors - the mansion was an electric marvel. Every device and system, basement to roof, was powered by batteries replenished continuously by a small-scale household electrical generator.
I wonder if Edison's Twentieth Century Suburban Residence was one of the inspirations for Buster Keaton's 1922 comedy "The Electric House".
Others are looking beyond gasoline altogether and there are already functioning solar hydrogen households. For example, Mike Strizki's Hopewell, NJ residence:
In 2006, the first Solar-Hydrogen Residence in North America was completed in Hopewell, New Jersey at the home of Mike Strizki. The home features an advanced solar-hydrogen system for hydrogen production and storage that is integrated into an existing solar and geothermal system, and provides for all of the home’s energy needs. The system also includes a hydrogen fuel cell vehicle refueling station.
Of course, you can generate low voltage DC electricity with a bicycle or hand crank too.
A newspaper article on how to unplug from the grid.