In the 77 days since oil from the ruptured Deepwater Horizon began to gush into the Gulf of Mexico, BP has skimmed or burned about 60 percent of the amount it promised regulators it could remove in a single day. The disparity between what BP promised in its March 24 filing with federal regulators and the amount of oil recovered since the April 20 explosion underscores what some officials and environmental groups call a misleading numbers game that has led to widespread confusion about the extent of the spill and the progress of the recovery.