With my corolla I saw a sizable gain, I think it was something like 3-5%. It was enough for me to keep it off. I tried the little mirror just inside the window and it didn't work too great. Visibility was good in the corolla, just had to look over my shoulder when changing lanes like you should already be doing. It's called the blind spot because you can't see it in your mirrors! The only issue I had with removing the mirror was for backing up, you can't see how things line up on that side of the car. It took a little bit to get used to, I drove through Detroit rush hour (to and from work) two days in a row for work with no problems, bumper to bumper traffic and you better be in the correct lane a good mile ahead of time kind of traffic.
