Don't use a mining excavator!
Intrigued by the damage done by the water, I investigated the excavator used. It's a Liebherr R9800 Mining Excavator. To get an idea of its size, compare the figures standing near it in the photograph below (click for a larger view).
The load bucket has a capacity of up to 42 cubic meters. One cubic meter of water weighs one metric tonne, or 2,200 pounds. Therefore, even allowing for the fact that one can't heap water like one can rock, and therefore the bucket may have been filled to only half its capacity, that still makes over 20 metric tonnes of water (or, probably, over 25 standard US short tons) that fell on the car!
Kinda explains the damage, doesn't it?