This was good enough to reprint, but it was written on Quora.com by Yuhao Ding, at this link.
Q: Why Haven't Car Manufacturers Yet Solved the Problem of the Blind-Spot in Side-View Mirrors?
A: Actually, they have. Drivers just aren't using the mirrors correctly. Most people adjust their mirrors such that they can barely see their own car in the mirror, and leave it there. Essentially, this causes a huge overlap between the side and center rearview mirrors, which is unnecessary. By spreading your side mirrors, you lose no information about what's behind you, but pretty much eliminate your blind spot to your sides. This new method (explained below) is recommended at most driving schools, including the BMW Performance Center in South Carolina.
Steps to readjust (consult images below):
Place the center mirror to show the whole rear-view window or at least as much of it as possible. Make sure you sit properly and aim the rear-view mirror without moving your head from the straight forward position.
Lean your head to the left until your face is almost touching the glass, and adjust the left mirror. While still leaning, your mirror should be far enough such that you can barely see the side of your own car.
Lean your head to the right until your head is over the center divider, and adjust the right mirror. Similarly, your mirror should be adjusted far enough such that you can barely see the side of your own car.
Re-evaluate. The idea is that there should be a small overlap between your side mirrors and the center rear-view mirror. If there is no overlap at all, then bring the mirrors slightly closer in. When sitting straight up, you should not be able to see your own car.
Now, you should have basically no blind spots. It takes a little getting used to, but you basically rely on your center rear-view much more than before. When a car leaves your center rear-view mirror, it should be immediately visible in your side mirror. Car and Driver has a pretty picture demonstrating this:
Even though I don't yet have a driver's license (I had one, but I went back to having a learner's permit because I don't have a car and the insurance is ridiculous), this is good information to know. Why don't they teach things like this in the Oregon Driver's Manual?