The record for the closest margin of victory in a car race is 0.0005 of a second, when Logan Gomez (USA) beat Alex Lloyd (UK) in the 16th round of the 2007 Indy Pro Series, the Chicagoland 100, at Chicagoland Speedway, in Joliet, Illinois, USA, on 9 September 2007.
The Indy Pro Series is the developmental racing series sanctioned by the Indy Racing League. The Sam Schmidt Motorsports cars of champion Alex Lloyd and Logan Gomez battled for the lead with Robbie Pecorari throughout the race, which was slowed by two extended caution flags, the first caused by a major crash involving Chris Festa and Jaime Camara and the second involving Travis Gregg and Wade Cunningham. Gomez led his teammate entering the final lap. Lloyd mounted a challenge and the two cars briefly touched exiting turn four and Gomez was able to hold off Lloyd for his first Pro Series victory by a mere 0.0005 sec.
Comments below may relate to previous holders of this record.