Tailgating is the action of a driver driving behind another vehicle while not leaving sufficient distance to stop without causing a collision if the vehicle in front stops suddenly. The safe distance for following another vehicle varies depending on various factors including vehicle speed, weather, visibility and other road conditions. Some jurisdictions may require a minimal gap of a specified distance or time interval. When following heavy vehicles or in less than ideal conditions (e.g. low light or rain), a longer distance is recommended. Causes There can be several reasons for tailgating. Preventing cut ins Tailgating can occur when a vehicle attempts to prevent another vehicle on the right or left from cutting in front of them. The tailgating (or preventing) vehicle will drive as close as possible to another leading vehicle to prevent the side vehicle from cutting in. Like all forms, this practice of tailgating is illegal and attempts to force the side vehicle to slow down and get into the line of traffic behind the tailgating vehicle. This practice is very likely to evoke road rage where one vehicle is blocking and another attempts to defy the block. Negligence Tailgating can occur because of a lack of perceived risk in so doing. Thus, it is done unconsciously or negligently, very often by people who consider themselves safe drivers and generally obey some other rules of the road. Evidence shows that more experienced drivers are more likely to be involved in rear-end collisions, possibly because they overestimate their skill and become complacent about allowing sufficient distance to avoid an accident. Coercion In its most uncivil form, it can be a case of road rage or intimidation. An example would be where the tailgating driver (the driver in the following vehicle) threatens damage to the leading vehicle and its occupants by driving aggressivelyperhaps also with use of headlights and hornto coerce the leading vehicle's driver into getting out of the way. The driver being tailgated might not wish to comply, especially if doing so would involve breaking the law, such as by increasing speed beyond the speed limit or changing lanes without due regard for safety. Aerodynamics A form of deliberate tailgating known as slipstreaming, "draft-assisted forced stop", or "draft-assisted forced auto stop" (D-FAS) is a technique used by some hypermilers to achieve greater fuel economy. D-FAS involves turning off the engine and gliding in neutral while tailgating a