Electro Energy Inc. (EEI), a leading provider of advanced battery technologies , today announced it is developing a custom-designed prototype battery pack for CalCars' Toyota PRIUS+ Test Vehicle, which is the centerpiece of the California Cars Initiative (CalCars) program promoting the commercial use and mass production of plug-in hybrid electric vehicles (PHEV). Ron Gremban, the lead technologist on CalCars' PRIUS+ project, stated, "Electro Energy's prototype pack ... is expected to improve average typical mixed-driving gasoline consumption and range performance to 90 mpg plus electricity for the first 40-50 miles after each charge, without compromising the Prius' original performance of 45 mpg."