Theoretically, a attacker can transmit an amplified message 300 m in 1 microsecond. So the car must limit the RTT to only a few dozen nanoseconds. This is fairl

Theoretically, a attacker can transmit an amplified message 300 m in 1 microsecond. So the car must limit the RTT to only a few dozen nanoseconds. This is fairly easy with modern electronics.