These days this expression has been extended to include any guard rail or bar used for protection of the body of a car. The nudge bar generally extends sideways from below the front end, finally bending upwards.
A bullbar or roo bar or nudge bar in Australia or moose bumper in Canada, and push bar or grill guard in the United States is a device fitted to the front of a vehicle to save its occupants from collisions, it could be an accidental collision with a large animal in rural roads or an intentional collision with another vehicle in police usage. They vary in size and form considerably, and are generally made of welded steel or aluminium tubing and even, moulded polycarbonate and polyethylene materials are now brought into use. The bull in its name refers to cattle, which in rural areas sometimes come onto rural roads and highways.
Studies have shown that cars with nudge bars cause an increase in the risk of death and serious injury to pedestrians. Unlike a bumper which absorbs some force and crumples, this happens because the nudge bar is rigid and so transmits all the force to the pedestrian. Because of the number of deaths and injuries caused by the solid fronts of cars, often with metal nudge bars (around 2,000 deaths are caused every year and 18,000 serious accidents per year in Europe), the sale of metal nudge bars that did not agree with the European Union Directive was banned.
A Push Bumper or a NERF is fitted to the body chassis of the car and is located at the augment front bumper which allows the car to be used as a battering ram for simple obstacles or fences, and even, to push disabled vehicles off the road.