In a passenger car with 3 mirrors (rear-view and 2 side mirrors), how do you set your side mirrors so as to see as much as possible?
The Click & Clack method:
Sitting in the driver’s seat (left or right-hand drive vehicle):
Driver’s side mirror
Lean your head against the window, and set the driver’s side mirror so that you can just see the side of your car in the mirror.
Passenger side mirror:
Position your head, as best as possible to the middle of the car. Use your radio, or center console as a reference. Now set your passenger side mirror so that you can just barely see the side of your car in it.
The difference? In my experience, most people seem to have their mirrors set narrowly (left) which has much overlap (blue area), what you get is more information per sq. in. of mirror (right):
Image taken from a good article on the subject.
It seems that a lot of driver education classes promote what I would call is the improper, narrow-view method. Perhaps for newer drivers it is easier for them to understand where things are in the mirror if they have their own vehicle visible in the mirror as a reference. I can’t see how that outweighs the clear benefits of the wide-view.
Using the wide-view method, you all but eliminate blind spots. The only things that can fit in your blind spot are small trolls that are attached to your rear quarters. You do not need to turn your head as far to check your sides. If you need to reverse into a tight spot, you simply lean toward the needed side to see more relevant visuals for backing in.
For some, this is controversial. I can’t see why. You decrease the amount of visual overlap, and increase the amount seen through the mirrors. That is, you only decrease the size of your blind spots (greatly). There is no drawback other than having to get used to the new positions, which is temporary.
Here's another good article.
None specific to this method, really. But keep in mind that this optimizes the view for the lanes adjacent to yours. Merging lanes coming in at an angle, or the 2 lanes over, visibility will be better, but you still need to shoulder-check those. Also, no guarantee that it works on all vehicle shapes and sizes.
When you set your mirrors with the Click & Clack method, if you find the (electric) mirrors won't adjust out far enough, try moving the mirror up or down and then try to go further out. Failing that, I wouldn't be afraid to gently push on the mirror if the electric motor won't adjust it quite as far as you need. As Nick mentioned, manufacturers don't quite get the Click & Clack method, so sometimes the mirrors won't adjust out far enough without a little trickery.