There's also a reasonable possibility that this was somehow personally motivated. Both of these young soldiers had just returned to their hometown after completing basic training. Basic training isn't a long enough time for grudges to die.
If there would have been explosives in the car, then yes, I think it likely would have been politically or ideologically motivated. As of now, almost anything's possible. But, I think we can safely rule out right-wing extremist, which is why this story is virtually invisible to the MSM.
You got that right. Sad isn't it?