A gravity racer or soapbox is a motorless vehicle which is raced on a downhill road either against the clock or against another competitor. The vehicles are propelled by gravity.

The Soap Box Derby is a youth-oriented soap box car racing program which has been running in the United States since 1934. Proclaimed "the greatest amateur racing event in the world", the program culminates each July at the FirstEnergy All-American Soap Box Derby World Championship held at Derby Downs in Akron, Ohio, with winners from their local communities travelling from across the US, Canada, Germany and Japan to compete. 2024 will mark the 86th running of the All-American since its inception in 1934 in Dayton, Ohio, having missed four years (1942–1945) during World War II and one (2020) during the COVID pandemic. Cars competing in the program race downhill, propelled by gravity alone.