Development of the production 500e started with prototypes assembled by hand at Chrysler headquarters in Auburn Hills, Michigan; the prototypes used components from suppliers (later announced as Bosch) and were shipped to Sonoma County, California (as the initially planned market was California) for testing in the summer of 2012. The Chrysler engineering team was tasked with integrating the hardware components and tuning the finished car to behave as close to a conventionally gas-powered 500 as possible. Some of the aerodynamic refinements developed for the production 500e were intended to be back-fitted to the regular 500.