The Packard motor grumbled quietly but menacingly in the enclosed space.

Others stayed where they were, grumbling quietly or exchanging desultory remarks.

Alien air whistled in and we grumbled quietly.

Some aides to the mayor grumbled quietly that the Council should have passed the bill earlier.

"I'll do more good over here," she grumbled to Rosethorn quietly.

"He will probably ram us into the next pirate in line," the wizard grumbled quietly as he walked away.

We found ourselves quietly grumbling to one another about menu offerings that promised more than the kitchen, on this occasion, seemed capable of delivering.

The silence stretched out for several seconds, almost a full minute, and more distant thunder grumbled quietly in the background.

They might grumble about the cold quietly among themselves, but they endured it.

"Haven't had to use one of these things in years," he grumbled quietly, and then turned the gun on himself, centering it carefully over his heart.