tailgate
v.to drive too closely behind the car in front of you. It is dangerous because you might hit them if they stop suddenly.
v.to drive a vehicle dangerously close to the rear of another vehicle. Often used in the context of aggressive driving or traffic violations.
“Don't tailgate the car in front of you.”
“The driver was pulled over by the police for tailgating a truck on the highway during heavy rain.”
“Aggressive drivers who tailgate often fail to realize that their reduced reaction time significantly increases the probability of a multi-car collision in stop-and-go traffic.”
The verb is both transitive and intransitive; it can take a direct object or be used alone.
From tail + gate. Compare liftgate.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.