I'd say it's hard to make a post-apocalyptic game without making people think it draws inspiration from Fallout 3.
Remember, Rage was first teased before Fallout 3 was released iirc. It was id's Tech5 showcase demonstration game.
However, I think they are bringing enough originality to the post-apocalyptic genre, and the driving aspect really brings a new level to the game. That, and it's a pure FPS. The dice-roll nature of Fallout 3 really bugs me sometimes - crossing FPS-aiming with RPG rules seems so wrong... but at least Fallout 3 is a pretty fun game, and as an RPG is still very enjoyable with a different twist. Just depends on how one approaches it - as an FPS, it's painful. But as an RPG, it has a different level of approach that is overall very fun.