"The vehicular attack sought to project a political message and sow fear beyond the immediate target of the violence. " 

Um, I see no evidence of that. One individual got carried away in the heat of battle and used his car to defend against the mob that was attacking his group. That is what risks happening when you have violent confrontations between groups, someone will go too far in either attacking their opponent, or defending themselves, and in the heat and battle, the difference between those actions get blurred.

That is a totally different scenario from someone coldly and calculatingly planning an attack in advance against people who are going about their business and in no way immediately threatening him. That is terrorism.