Not sure how, you arent destroying evidence or preventing the cop physically from searching, nor are you even violating any directives. You've just made the situation such that if he wants to search it will be illegal.
That would be like saying not giving a police officer permission to search my house by closing my shades is obstruction of justice.
It will be, the car is also the evidence isn't it? Also the "slasing of tires" will be more of a problem for more probable cause. And the timing will likely point to mens rea for obstruction. The premise is also wrong i suppose i need to look more. But i think the focus of the vehical search doctine focuses on the vehicals as class of redily mobile locomotive. It can be argued that no matter what you do to a car, a car is redily mobile as long as someone can fix it.
Tho US laws are not my thing let me know if you find some concrete amswer.
