Any act of violence designed to affect political change is “terrorism.”
If we use that weird definition then, we have to know his intent. We can therefore infer it wasn't terrorism since it obviously couldn't have been premeditated. He would have run them over at the start of the rally, not at the end of the rally when there were street battles going on everywhere, including people being attacked on their way to cars, and the cars being attacked as well.
I think the biggest mistake was to look for a definition of terrorism that was different than the following:
"Terrorism is whatever Muslims do against non-Muslims."