This is so they can have "twice as many demons" pestering you. He pushed for Rage to have 60 across the board because of the racing segments 'needing it'.
In Doom 4, "we decided the multiplayer is 60 frames per second, but the single-player is 30 frames per second, so you can have twice as many demons coming at you," explained id's technical wizard, John Carmack who's leading development on id Tech 5.
"They're valid decisions to go each way, but I am proud of the fact that we were able to push Rage through at that field," he continued.
"And part of it also was because in a driving environment, you notice 60 frames per second a lot more than you do when you're just walking around. So, that was also part of the deal -- it made it more important to be 60 frames per second."
Check out thebetween John Carmack and Gamasutra, where the id Software veteran discusses a host of technical topics and even where predictions went wrong. Rage releases on Xbox 360, PS3 and PC October 4th in the US, 7th in Europe.