Simplify the following text for a Grade 9 native English-speaking person.
Original: Conversion kits and services are available to convert production model hybrid vehicles to plug-ins . Other plug-in vehicles ongoing demonstration trials or slated to the market for 2011 and 2012 are the Fisker Karma , Toyota Prius Plug-in Hybrid , Ford Escape Plug-in Hybrid , Volvo V70 Plug-in Hybrid , Suzuki Swift Plug-in and the Ford C-Max Energi .
Simplified: Plug-in hybrid cars are also known as plug-in hybrid electric vehicles or PHEVs .