First, any professional peace officer is going to come through that window and stop the smoking plan in short time. In my town, theyd have the SWAT team do that. You would then be charged with possession for sure because they'd have what you hadn't yet smoked.

But any police department or DA worth its salt isn't going to be as worried about the possession charge as it would be about the worse offense, which would be evading police and resisting apprehension and arrest. They'd then add on the concomitant possession charge to lengthen your sentence. You'd have higher bail, pay higher fines and be sentenced to longer time served/probation.