The "night" picture was taken by making the aperature very small and the shutter very short. I wanted to make it dark enough that you could see the color.
Note that the flash on the A80 is very close to the lens, so the results you see here are appropriate for a car that is very far away. I need to take some other pictures with the light source farther away from the lens to simulate a car at 50-200 feet. I also need to take the same set of pictures from an extreme angle. (what do reflectors on the side of a bike look like from behind?)
Also note that these pictures only show the relative brightness, not absolute. The absolute brightness is dependant on some other factors like the angle of the reflector with respect to the observer and the intensity of the light source.
The DOT stuff was some stuff I got at Home Despot and couldn't find more of it (I guess they couldn't sell 10 million items so they dropped it.) Anyway, I expect it's the same as the stuff you can get anywhere else (like LabSafety.com or eBay)