Car side and rear-view mirrors are designed to give you a view around your car, but they typically don't show you the two spots directly to the side of your car (the "blind spots"). Luckily, you can increase the field of view of your side mirrors by over 200%1 and virtually eliminate blindspots by adding aftermarket blind spot mirrors.
The problem
Here's a photo of the view through my side mirror. Looks safe to merge left!
Oops! Turns out there's a car right next to me that I didn't see at all.
The solution
With a 2" convex mirror attached to the side of my existing mirror, I can suddenly see everything in the blind spot.
Costs
Blind spot mirrors are incredibly cheap. I bought mine as a two pack at a gas station for $5 a few years ago, and you can buy them for less than $10 on Amazon.
Which ones specifically?
My blind spot mirrors are fixed with a black border. Being fixed in place makes them low maintenance, and I haven't touched them since they were installed years ago. I like the black border because it makes it easy to find them at a quick glance.
I can't find any that are exactly like mine on Amazon, although these borderless ones are similar. I suspect you'll find ones like mine at any sufficiently-large gas station.
I'm skeptical that adjustable mirrors will stay in place in 75 mph winds, but people on Amazon seem to really like these adjustable ones, and I plan to try them out on my fiancée's car.
Placement
You'll get the best field-of-view enhancement by placing the blind spot mirrors to the outer edge of your existing mirrors, and you should be careful not to cover any useful parts of the existing mirrors. I prefer to put mine in the outer top corners (like in my photos), but I've seen people suggest any corner of the existing mirrors that won't get in the way of the existing view.
Also, if you have an existing blind spot detection system (with lights or an alarm), make sure you don't cover anything it needs to work properly (I'm not very familiar with these, so I'd err on the side of caution and not add anything to your mirror unless you know it's safe to do so).
Mirror adjustment
You should also consider adjusting your side view mirrors to reduce blind spots on their own. You should adjust your mirrors at a minimum to they barely don't show the side of your own car (this is how I prefer them with a blind spot mirror), or go even further and make them only show your blind spot, which reduces the need for blind spot mirrors on sufficiently small cars.
A research caveat
While researching this post, I was able to find research showing that blind spot mirrors significantly increase your field of view1, but I wasn't able to find any direct research on whether using these reduce the risk of crashes. This is very annoying, but I think it's likely that being able to see better will make your driving safer. Please send me an email or leave a comment if you happen to know of more direct research on this.
Final thoughts
The benefits of installing a blind spot mirror are clear: they're cost-effective, they drastically improve your field of view, and they simplify changing lanes. Although there's no direct research linking them to a reduced risk of crashes, the advantages they offer in visibility compared to their low cost make a compelling case for their use.
- Hassan, M., Tan, F., Abdullah, M., Radzuan, N., & Abu Kassim, K. (2020). Does a Circular Convex Blind Spot Mirror Increase the Driver’s Field of View?. Journal of the Society of Automotive Engineers Malaysia, 4(1). Retrieved from http://jsaem.saemalaysia.org.my/index.php/jsaem/article/view/117 ↩