Bumpers
A bumper is a part of a car designed to allow one vehicle to push another and to withstand the impact from collisions. Brush guards, push bars, etc. more...
were added "after-market" to bumpers of automobiles, pickups, trucks, and utility vehicles since at least the 1920s to provide additional protection to the vehicle. And while bumpers were originally made of heavy steel in later years they have been constructed of rubber, plastic, or painted light metal leaving them susceptible to damage from even minimal contact. For the most part, these vehicles cannot push, or be pushed by, another vehicle. An entire after-market industry has developed which now produces various guards to protect these vulnerable modern bumpers.
The fun of bumping one car into another led to the creation of bumper cars at amusement parks. These small cars are designed to fit one or at most two people and crashed into each other consistently.
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