Weighs down car

Mouse's tail wagged even more at the mention of hot dogs. He chuffed out a breath, nudged my hip with the side of his head in a fond gesture, and we went outside to wait for Murphy.
She pulled up and eyed Mouse warily as I opened the back door and he jumped up onto the backseat. The car rocked back and forth with his weight and sank a little.
"He's car-broken, right?"
Mouse wagged his tail and gave Murphy an enthusiastic, vacant doggie grin, tilting his head back and forth quizzically. It was easy for my imagination to subtitle the look: Car-broken? What is that?


Proven Guilty Chapter 15, Page 106-107