I don't use my side view mirrors to find out if someone is in the lane next to me. I use them to continuously scan around my vehicle at all times. If and when I decide to make a lane maneuver, I already know exactly where the cars are in the next lane and that there is a spot for me to move into. I take one last check in my side view mirrors to make sure someone didn't change lanes into the spot I'm looking to take. Properly set up, you should have virtually no blind spots in your mirrors.