OK, after installing it in the Crossfire, and with about a month of driving with it in the HHR, here's how it has worked for me:

Sundown to sun up, it's da bomb, works great. HOWEVER, in bright sunlight, the fact that it reduces the image so much makes it difficult for these tired ol' eyes to see the color of the traffic light - it's just too small.

Dawn, dusk, or at night, the traffic lights are bright enough to really stand out, and it's easy to see them. In the full light of day, not so much...

They'll stay in my cars, as they are not intrusive at all, and don't really affect the normal line of vision. I don't regret the purchase, because they do work well at night or in low light.

Would a I get another one? For a night cruiser, certainly. For a sunny day commuter, probably not.