This depends on his criminal history, was anyone hurt and how much damage was done to other's property. Stealing a car is grand theft auto, and it's not a game. He will probably do some time but we are not sure how much.
https://www.inmateaid.com/ask-the-inmate/if-you-steal-a-car-and-go-joyriding-how-much-time-will-you-get#answer
Accepted Answer Date Created: November 23,2015