2012 McLaren MP4-12C - Development Continues - The latest experimental prototypes (XP) are currently being tested at various locations across the globe. To fuel the fire of anticipation, McLaren has released a new video of the XP Beta cars flying low around the foothills near Tarragona, Spain. The cars featured are XP8 and XP10, which are powered by a tweaked M838T twin turbo engine.