Bump and run (auto racing)
Bump and run is a technique for passing mainly used in stock car and touring car racing, which eventually inspired the police PIT maneuver. While the bump and run maneuver is not uncommonly used in series such as NASCAR, it is dangerous to use in open-wheel racing in general due to the extremely high speeds and relative fragility of open-wheel race cars. A trailing car intentionally bumps the rear bumper of the car in front of it. The bump sometimes causes the lead car's rear tires to momentarily lose traction. The driver  of the lead car is forced to correct his steering, slow down, or at least stop accelerating to regain traction and/or car attitude. The trailing driver positions to pass the leading car before the next corner. Bump and run is often done after coming off a corner. It is much more dangerous when done in the middle of a corner because both cars are already loose. A gentle tap is what is required most of the time. A stronger bump might result in the lead and/or the trailing car spinning out of control, and possibly leading to a multi-car  crash. Car of Tomorrow. Introduced in 2007, NASCAR's Car of Tomorrow was expected to hinder the effect of bump and run. The rear bumpers on the cars were lowered, while the front bumper was raised. With this configuration, when a trailing car hits a car in the back, the contact is square, and the leading car's rear wheels are not lifted off the track.