 As of mid-2010, and in advance of upcoming legislation, some carmakers announced their decision to address this safety issue shared by regular hybrids and all types of plug-in electric vehicles, and as a result, the Nissan Leaf and Chevrolet Volt, both launched in late 2010, and the Nissan Fuga hybrid and the Fisker Karma plug-in hybrid, both launched in 2011, include synthesized sounds to alert pedestrians, the blind and others to their presence.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).