I would suggest building the brackets in Illustrator and choose to continually rasterize the image, that way you won’t have any degradation in their look if they scale up. 3d space all the elements (except the car footage) and parent the text to the brackets so they move together.
Use the motion tracker to match the movement of the car. Copy the keyframes onto the position of the end point of the line (or use an expression). Unfortunately there’s no way to track the motion in 3d inside of AfterEffects so you’ll have to fake it. One way I’ve found that works well is to have a 2d object that scales up and down matching one object in the scene (in the case of the smart key text just put an object over the door handle). Once you’ve got that keyframed properly just use an expression that has your z-position match the scaling of the object. That way it will give the impression that it is moving forward and backward in sync with the motion of the car.