Going by the patent filing, its main goal appears to be a better representation of a vehicle's width in a lane.
Have you ever had a lane departure warning system start shouting at you, when you were absolutely sure
you weren't venturing out of the lane? What if you had a head-up
display that instead could relay that information to you in real time
using augmented reality? That's what one of Toyota's recent patents
looks to do.http://www.cnet.com/roadshow/news/toyota-patents-trick-augmented-reality-windshield/