If you really must know what it does... Fine.

The clue for its purpose lies in the video. He says he has radar and laser gun in the vehicle for testing purposes. Obviously if you have a cop shooting laser or radar its coming from in front of you, hence why its mounted in front. Infrasonic waves distort the atmosphere as they travel through it. Radar and laser guns shoot out a signal that it reads as it bounces off an object and comes back. Distort the atmosphere that those waves travel through and the wave will dissipate or be dispersed thus the gun will have an erroneous reading unlike when it is being jammed. Very sneaky, minus the whole "Hey what the hell is that box mounted on the front of your car?" thing.

However infrasonic waves at low frequencies do cause discomfort, nausea, dizziness, feelings of anxiety, etc, and at ultra low frequencies like 7 hertz can cause death. Now I doubt he is using it to blast infrasonic waves into competitors vehicles to make them shit their pants, but I'm not about to test that theory by cutting him off in traffic either. If by some rare unrealistic chance that is its purpose, depending on the state he uses it in and is successful, he could cause a fatality and receive the death penalty.

BTW: In the video he mentions having strobe lights. The purpose of those in a Bullrun setting is if anyone is behind you and you are running lights off with infared, the strobe lights rearward makes infared useless to your opponent.