He’s brought with him new, modern, ways to train racers, but that doesn’t necessarily mean that he’s entirely a “new school” sort of guy.
According to Entertainment Weekly, Nathan Fillion’s Sterling is now the man in charge.
In the original Cars, the Rust-Eze company was run by Rusty and Dusty (the voices of NPR’s Car Talk) but it seems that they will apparently not be the owners anymore when we see Cars 3.
He’s described as somebody who is about the same age as Lightning, but has his finger on the pulse of modern racing and understands what needs to happen to get ahead.