A lane assistance system for providing a fast rearwardly approaching vehicle output or an extremely fast rearwardly approaching vehicle output in response to a rearwardly approaching vehicle nearing a host vehicle, the system comprising: at least one rear sensor unit disposed proximate to a rear of the host vehicle, the at least one rear sensor unit configured to detect at least one of a distance and a velocity of a rearwardly approaching vehicle moving toward the host vehicle; and an electronic controller configured to: obtain host vehicle velocity information, obtain at least one of a distance and a velocity of a rearwardly approaching vehicle, determine a relative velocity of a rearwardly approaching vehicle in relation to the host vehicle; when a lane of a rearwardly approaching vehicle is obtained via the at least one rear sensor unit, upon determining that (a) a rearwardly approaching vehicle is within the same lane, or at least one neighboring lane on either side of a host vehicle lane that the host vehicle is traveling in, and (b) the relative velocity indicates a rearwardly approaching vehicle is approaching the host vehicle at or greater than a fast relative velocity threshold, providing the fast rearwardly approaching vehicle output, the assistance system characterised in that said electronic controller is further configured, when a lane of a rearwardly approaching vehicle is not determinable due to a lack of angular resolution for the rear sensor unit, and upon determining that a rearwardly approaching vehicle has a relative velocity that is at or greater than an extremely fast relative velocity threshold, to provide the extremely fast rearwardly approaching vehicle output. at least one rear sensor unit disposed proximate to a rear of the host vehicle, the at least one rear sensor unit configured to detect at least one of a distance and a velocity of a rearwardly approaching vehicle moving toward the host vehicle; and an electronic controller configured to: obtain host vehicle velocity information, obtain at least one of a distance and a velocity of a rearwardly approaching vehicle, determine a relative velocity of a rearwardly approaching vehicle in relation to the host vehicle; when a lane of a rearwardly approaching vehicle is obtained via the at least one rear sensor unit, upon determining that (a) a rearwardly approaching vehicle is within the same lane, or at least one neighboring lane on either side of a host vehicle lane that the host vehicle is traveling in, and (b) the relative velocity indicates a rearwardly approaching vehicle is approaching the host vehicle at or greater than a fast relative velocity threshold, providing the fast rearwardly approaching vehicle output, the assistance system characterised in that said electronic controller is further configured, when a lane of a rearwardly approaching vehicle is not determinable due to a lack of angular resolution for the rear sensor unit, and upon determining that a rearwardly approaching vehicle has a relative velocity that is at or greater than an extremely fast relative velocity threshold, to provide the extremely fast rearwardly approaching vehicle output. obtain host vehicle velocity information, obtain at least one of a distance and a velocity of a rearwardly approaching vehicle, determine a relative velocity of a rearwardly approaching vehicle in relation to the host vehicle; when a lane of a rearwardly approaching vehicle is obtained via the at least one rear sensor unit, upon determining that (a) a rearwardly approaching vehicle is within the same lane, or at least one neighboring lane on either side of a host vehicle lane that the host vehicle is traveling in, and (b) the relative velocity indicates a rearwardly approaching vehicle is approaching the host vehicle at or greater than a fast relative velocity threshold, providing the fast rearwardly approaching vehicle output, the assistance system characterised in that said electronic controller is further configured, when a lane of a rearwardly approaching vehicle is not determinable due to a lack of angular resolution for the rear sensor unit, and upon determining that a rearwardly approaching vehicle has a relative velocity that is at or greater than an extremely fast relative velocity threshold, to provide the extremely fast rearwardly approaching vehicle output.