Radical SR9 chassis number 4 was raced by Van der Steur Racing and competed a total of nine times in the 2006 , 2007, 2008, and 2009 American Le Mans series.  Its first race was in September 2006.  It had an AER P07 L4 1995cc turbo engine and was raced in 2006 with a blue/black livery, and in 2007/2008/2009 with a blue livery.  In 2023 this car was located in Maryland U.S.A..