Greg Biffle's closest friends are speaking out after the NASCAR driver and his family were killed in a plane crash. "This will be one of my favorite videos of all time," digital creator Garrett Mitchell wrote via Facebook on Thursday, December 18, with video from a recent race. "A wheelie side by side with the Biff. This is the worst day ever." Just hours before posting a throwback video with Biffle, Mitchell confirmed in a separate social media post that the 55-year-old motorsports legend and members of his family died.