Mystery Lexus LFA Prototype Video

New video footage has surfaced of the mysterious Lexus LFA prototype which was captured by spy photographers last week:

Upon viewing the vehicle in motion on the streets of Southern California, more questions arise: is the quiet sound indicative of the media speculation that this is a plug-in hybrid prototype?  Are the aft-mounted radiators from the production LFA removed, indicating that this is a possible test mule for a vehicle other than the LFA? A second video is available after the jump.