No doubt, that 2 front 2 rear is the best setup if you want to be bullet proof.

With that being said, 1 is better than none if you are on a budget.

I have 2 ALP up front and 1 ALP on the rear of my BMW.

This past weekend in testing, I was 100% JTG on the front on all 5 guns we used: Stalker LZ1, PL3, PL2, Marksman, Truspeed and TruSpeed S.

With the single sensor on the rear, I was also 100% JFG with all guns, with the TruSpeed S being the only exception. I was JFG even on the TruSpeedS on passenger rear and center mass with 1 punch through. They got my speed at will on the drivers tail light.

I will eventually get a 2nd sensor on the rear to shore up any holes.

In GA, only state patrol can shoot at rear. Fortunately for now they use PL3, where I am 100% protected on the rear with the single sensor. I would not feel so comfortable in an area with the TruSpeedS.