Only if your sense of scale has stopped functioning. It is a dangerous journalistic prank that probably does deserve a telling off from traffic cops, to much the same level as someone who is drunk driving. But I think trying to classify it as terrorism is not helpful or particularly sane.

Seeing as how drunk driving kills a very large number of people every year and is now punishable by imprisonment and extremely steep fines, you might be onto something here.

If people were screwing with cars like this as often as drunks were driving, I think you would end up with mortality figures that were at least in the same ballpark.

At what scale would you consider it to be terrorism?

To my mind, it would have to be some form of an attack, if untargeted, at least hundreds of cars, and if small would have to be targeted and strongly political, dangerous stupidity in a single instance for the purposes of having a good press story, doesn't qualify as either causing terror, or having an intent to, notwithstanding the broad legal definition that has been adopted over the past 15 years.