I have a four month old female ESS. While she is full of energy, she rarely exhibits other than playful aggression and is typically docile and loving. With one notable exception. She rides with me in the passenger seat of my truck and while in motion she stays calm and content. But when I stop to get out, say at the grocery store, she comes unglued! Barking wildly, charging into my lap, and trying to get out. I literally have to fight her off and, even at only 16 pounds, she can be formidable. Once I escape and close the door she is fine. She does not bark or carry on while I'm gone, just watches out the window for me. Any suggestions on how to address this behavior would be sincerely appreciated.