In 2000, the NHRA mandated the maximum concentration of nitromethane in a car's fuel be no more than 90%. In the wake of a Gateway International Raceway fatality in 2004, involving racer Darrell Russell, the fuel ratio was reduced to 85%. Complaints from teams in regards to cost, however, has resulted in the rule being rescinded starting in 2008, when the fuel mixture returns to 90%, as NHRA team owners, crew chiefs, and suppliers complained about mechanical failures that can result in oildowns or more severe crashes caused by the reduced nitromethane mixture. They also mandated enclosed roll cages.