 Toyota introduced its Vehicle Proximity Notification System (VPNS) in the United States in all 2012 model year Prius family vehicles, including the Prius v, Prius Plug-in Hybrid and the standard Prius.There is also aftermarket technology available in California to make hybrids sound more like conventional combustion engine cars when the vehicle goes into the silent electric mode (EV mode).In August 2010 Toyota began sales in Japan of an onboard device designed to automatically emit a synthesized sound of an electric motor when the Prius is operating as an electric vehicle at speeds up to approximately .