I read somewhere, years ago, about someone creating Min-Min lights by bounching a powerful light at an low angle under the proper atmospheric conditions. If I stumble across a link, I'll let you know.

The interface between two air masses can refract light in strange ways, and I believe that a lot of the Shimmering Light Observations (SLO) are due to this effect.

That your sighting occured at sunset makes me suspect something like this. I also note that you said the light moved west, then up.

The San Luis Valley in Colorado is known for sightings. It is also known for inversions (trapped warm air in the valley) and for a very straight highway with hills. Combined with the headlights of south-bound cars, I could see how this would produce intersting atmospheric lights.