I hope he "your friend" has a hefty amount of cash stashed somewhere. With that I mean over 20,000 Dolores. (20 k) (I know Dolores not dollars)
DUI will cost close to 10 thousand, between fines, lawyer fees, court fees and so on. Then he will be paying for a long time with a special form called SR-22. From now on, any insurance company will request his SR22 and that automatically will place him as a HIGH RISK driver. So even if he skips jail and pays all the fines, his insurance will take care of the rest.
And I have no clue how is he going to pay for the rental vehicle.
He should be glad he impacted a vehicle and not a human being.
Word of advice, tell your friend not to drive for the next 5 years because insurance alone is going to hurt his pocket the most.