Awesome. Exactly what I was looking for. I couldn't find the actual regulations before. Thank you, Bonus points to you.
I have the original Certificate of Origin as well. You are correct I have European/Spanish plates. As well I have the military registration paperwork to drive on the Euro plates. I was stationed in Colorado before and as far as military and registration is concerned they discount the ownership tax, but if the vehicle is purchased in state then sales taxes are due.
Did you ship through BMW or the government back to the states? Mine is going through the BMW home shipment program. That sucks your car had to sit. I have a bill of sale dated in August so we'll see.
This is what I could find concerning sales tax of vehicles purchased outside of Colorado per their regulations in the link you provided.
"(2) The following shall be exempt from taxation under the provisions of part 2 of this article:
(a) The storage, use, or consumption of a motor vehicle, if the owner is or was, at the time of purchase, a nonresident of Colorado and the owner purchased the vehicle outside of this state for use outside this state and actually so used it for a substantial and primary purpose for which it was acquired and the owner registered, titled, and licensed said motor vehicle outside of Colorado."