speed of light

if any observer moving slower than the speed of light observes the speed of light to be a constant, does that imply that any observer moving at the speed of light observes anything moving slower than the speed of light to be moving at the speed of light, relative to itself?

i.e.:  if light could measure, would it observe a car and a comet to be moving at the same speed?

Cannot achieve speed of light.
Light only moves at light speed because it has no mass.
Any mass would require an infinite amount of energy to accelerate.
Divide by zero sort of thing.