You can choose a super power, but the first person to reply can name a side effect.

But you can only change the light after you’ve gone through it

You're the only one who is able to see the changes.

Edit: I decided that a superpower which only alters your perception is not really a superpower, so let me improve it: All drivers who have the same eye color as you will be able to see the changed colors. Other drivers will see the original colors. Enjoy!