Demand for the conversions are so strong that a handful of companies are now supplying such kits, promising to boost mileage of hybrid cars like the Prius to more than 100mpg while also enabling the cars to travel distances of more than 20 miles on electricity alone, reports Automotive News.
The conversion requires installing extra batteries that can be charged up by regular household outlets. The technology is still in its infancy and its unknown how long the batteries will last.
GM and Toyota are two of the major carmakers currently developing plug-in hybrids but the release of such a model from either company is at least several years away.