How discreet is a dry herb vaporizer+a professional sploof?

I’m going on a road trip to New York with my parents and they don’t care if I smoke weed, they just don’t like seeing it or smelling it. So if I where to go under a blanket in the back of my car and blow the smoke from a dry herb vaporizer through a sploof would they be able to smell it? Don’t put down an answer unless you’re actually going to answer the question, please and thank you : )