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?

>>3
flawed thinking, not relevant to the question, and a dumb way to go through life.