What is an indication with just the eyes called?

Question

Imagine yourself driving a car and and spotting someone on the sidewalk. You stop the car beside him and want him to get in the backseat. You say something like "Hey, get in," with a nod of head that indicates that you want the person to get in the back. It is the 'nod' that I am stuck with. The same kind of gesture and motioning can be done with just eyes too but I don't know how to write it. What I really want the reader to imagine is someone just briefly jerking their head in the direction of the back door. So far, I have this. The context is somewhat menacing; it's not a pleasant invitation. >The car came to a halt beside me. >“Let's go for a ride,” he said, **throwing a glance over his shoulder to the back.** “Get in.”

Answer 1

How about something direct like: "gesturing toward the backseat with savage eyes"? If you don't like "savage," you could use brutal, cutthroat, furious, bloodthirsty, etc...

Hope that helps!