A mechanic was killed Tuesday when a car lunged forward and rolled on top of him, according to the shop’s owner. Robert Stokes, 60, of Bogart, was pronounced dead on the scene around 1 p.m. Tuesday, when a car on a slight grade is believed to have slipped out of gear. Stokes was working with a customer while standing in the Parks Import Service Center driveway on Dawsonville Highway in Gainesville, Hall County Sheriff’s Office spokeswoman Deputy Nicole Bailes wrote in an email Tuesday.