Done exactly that. Stop the car and nothing happens until they behave. It works!
My 1 yr old grandson is one of the Babies Who Lunch. He feels the vibe of a fine restaurant and does his charming baby thing, enchanting one and all. He will find that being a terrible two is not OK when we go out.
And, yes, he loves his Mimi.
When it was explained to her, her response was "Oh...we call that disobedience."