CHULA VISTA — A young man accused of driving drunk and causing a crash in National City that killed his 19-year-old passenger pleaded not guilty Friday to gross vehicular manslaughter while intoxicated and other charges. Oscar Munguia, 20, is accused in the Feb. 15 death of National City resident Leslie Lepron, who was riding in the back seat when the vehicle crashed on East Plaza Boulevard near Interstate 805 at around 1:30 a.m. Deputy District Attorney Hailey Williams alleged that Munguia was driving without a license and was going faster than 75 mph at the time of the crash. The prosecutor said the defendant’s blood-alcohol content was measured at about .13 percent shortly after the crash. In California, it is illegal to drive with a blood alcohol content of .08 percent or higher.