Isn't This Cool?

From the  New York Times:

Andrew Sacks for The New York Times Ron Gremban modified a Toyota Prius by installing auxiliary batteries.	Andrew Sacks for  The New York Times Felix Kramer, left, and Ron Gremban in Ann Arbor, Mich., with an auxiliary battery charger for a converted Prius. Toyota has spent millions persuading people that the car does not need to be plugged in.

These Ann Arborites have modified a Prius in two ways: It has extra batteries, so can run farther on battery power alone; and it can be charged by plugging it in to a wall outlet.  Apparently, Toyota discourages these modifications, calling them unnecessary.  Critics point out that 60% of electrical power is generated via the burning of coal, which is more polluting than gasoline.  However, there are advantages.

[...]They were aroused by a mysterious unmarked button on their Prius and discovered that in Priuses sold in Europe and Japan, the button allows the car to drive for a mile in electric-only mode. Mr. Hermance said the feature was disabled in Priuses sold in the United States because of complications it would have created in emissions-testing rules.

Mr. Kramer said "a bunch of engineers reverse-engineered it in the United States and figured out how to hack it."

But they soon wanted to travel on batteries for more than a mile and began to collaborate through CalCars on adding batteries to the Prius that would allow for longer pure electric travel. With the help of dozens of volunteer engineers collaborating online, the group retrofitted a Prius in Mr. Gremban's garage to travel about 10 miles on nothing but battery power. [...]

This would be great for urban use: drive to the city in normal mode; in the city, use electric-only mode.  That would cut down on air pollution in the city, where it tends to be most concentrated, and causes the most health problems.

Another advantage is that the cars usually would be plugged in at night, drawing electricity at times of low demand.  What would be really cool would be a way to plug the car into a heavy outlet in the home, so that you could use the car to power the house, in case of an electrical outage. The article mentions the possibility of car owners selling electricity back to the power company, although I doubt that would be efficient enough to be worthwhile.