The bike is too small an element in the overall picture to matter much. If I had to assign importance to various elements, I'd say that your shirt or jersey is most important, followed by whatever is covering your rear end.

If you really want an idea of what you look like to a driver ask a friend to ride his bike past you and note what you see as he fades into the distance. To do this right, you should stand out in the road at the left tire track so you line up with where a car's driver would be. While you're at it, note how the bike's lane position affects how much it stands out against the background.

At night, it's all about lights and reflectors so the bike certainly doesn't matter.

IMO - every cyclist should do this "what do I look like from the driver's seat" exercise both day and night and under various lighting conditions, especially heading into a low sun.