Why is the team confident it can reach 400 mph? They have already gone 376.363 mph on September 25, 2010, so they need another 25-plus mph to hit the big number. Aside from the effect of a longer acceleration distance, a 12 percent drag reduction is expected from Salar de Uyuni’s 12,000-foot altitude. Drag is directly proportional to air density. Also, in the past the streamliner’s tapering tail has been incomplete. A pair of “doors” located under the drag chute tube at the rear have “for various reasons,” according to Akatiff, not been able to be used during previous record runs.