I would think that a hummer or an old pickup truck with good tires would be the ideal weapon. All you have to do is get a good running start and thnunkthunkthunkthunkthunkthunkthunkthunk! No muss, no fuss except for a trip to the car wash to get the poop,hair, and brains off the hood. Definitely not something you would want to do with a convertible. With all the body parts flipping over the hood it would rapidly end up looking like a bucket of the Colonel's Original Recipe gone rank.
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Those who use arms well cultivate the Way and keep the rules.Thus they can govern in such a way as to prevail over the corrupt- Sun Tzu, The Art of War