Driving to the Huntington Beach International Surf Museum for an exhibit opening and heard this sound that I thought was a motorcycle trying to pass me on the right. Then, all of a sudden I caught a glimpse of a plane in my open sunroof. After that it was kinda of a blur. I ultimately pulled up to the plane and looked over to the pilot and she was on the radio to the tower, I gave her a thumbs up and she gave one back with a wave like "I'm okay." By then the Police and Fire showed up and since there were other witnesses I left to head to the museum. There were no injuries, no fire, no accidents, nothing. A perfect landing by, what I understand to be, a student pilot with about 20 hours of solo time. Not sure the cause of the power loss.