I'm definitely going for the second option here, taking away the ability to injure is most definitely going to devalue shooting noticeably, which would consequently reinforce race leaders even further and significantly decrease the likeliness of overtaking said leaders, especially when they're well acquainted with the flow of things.

I'd also add to this the notion of reconsidering how player-to-player collisions should behave, because honsetly it's plain frustrating needlessly at times especially at the brief start of a race or fighting over a vertical pole. I suggest either removing it altogther or, at the very least, have a prolonged duration of total invulnerability at start to make it fair game.