On Tuesday, A123 Systems announced that it has started taking online orders from those Toyota Prius owners who want to switch from hybrid to plug-in hybrid. This can now be done by getting the new L5 battery module. However, it isn’t the cheapest of operations, as the battery and installation cost $9,995, to which $400 are added for taxes and a "destination fee." A date when the battery is to be made available hasn’t been announced yet.

Drivers of Prius models made between the years 2004 and 2008 will be able to place the battery in the spare tire slot in the trunck. According to A123 Systems, the extended-life battery comes after 200,000 miles’ testing in "real life" conditions, and by using it, cars may get as much as 100 miles per gallon of gasoline.

As Felix Kramer, founder of CalCars.org, says, there aren't that many plug-in hybrid cars cruising the U.S. roads at the moment and most of the owners are research institutions.

Companies such as GM and Toyota have been working on the development of plug-in hybrid vehicles but it seems that the technology is still too expensive to be implemented it at a larger scale. For those currently using it, the environmental issue is probably more important than that of gas money savings.

Toyota sold 2.621 million cars in the US in 2007, surpassing Ford Motor Co for second place behind GM. A spokesman said that sales of 2.69 million vehicles are expected in 2008. At the beginning of the year Toyota officials restated the company’s commitment to bring plug-in hybrids on the market by 2010.