Ford pulled strangers off the street at Irwindale Speedway in 2017, handed them a new Mustang, and told them to make smoke. The occasion was line lock becoming standard on every 2018 Mustang, four-cylinder EcoBoost models included, not just the V8 GT. Here is exactly what the system does to the brakes, why drag racers have used the trick for decades, and the fifteen-second limit almost nobody mentions.