According to Official Guinness Records,
In 2005 scientists at Rice University, USA, led by James Tour, revealed a "car" made from a single molecule of mostly carbon atoms that contains a chassis, axles and four wheels made from buckyballs. The entire assemblage measures just 3-4 nanometres across, slightly wider than a strand of DNA.
For a complete list of 2005 records, please visit 2005 Guinness Records in United States.