With the G.E.P.:
If you throw something straight up it will go directly up and directly down.
According to you anyway.
But if someone is watching you throw it, and you're moving, they'll see it moving on an arch.

The penguin follows you and lands in the car, even though you're moving.



Without the GEP:
If you're in a moving car and you throw something straight up, it goes straight up.  From your point of view it whips backwards, as you move away from it.

The penguin falls back to the ground where it was originally thrown, at which time the car is long gone.



Most people intuitively know the G.E.P., even if they can describe it in terms of vectors and momentum.  All the same, it's a rare person who (when presented with the fact) will jump out of a car on the highway and expect to hit the ground without following the car for a while.