Q: Can a person be charged with “eluding” if the officer never turned on his sirens, lights, or used any other method?

A: The answer is no.

The law says "knows or reasonably should know that he or she is being pursued" is the felony statutory language.

"...Who has received a visual or audible signal such as a red light or a siren from a police officer driving a marked vehicle showing the same to be an official police, sheriff, or Colorado state patrol car directing the operator to bring the operator’s vehicle to a stop, and who willfully increases his or her speed or extinguishes his or her lights in an attempt to elude such police officer, or willfully attempts in any other manner to elude the police officer, or does elude such police officer commits a class 2 misdemeanor traffic offense" is the traffic offense of eluding.

A: I agree with Mr. Smith's answer below. However, one thing I would add is that the case law on Eluding does not make Mr. Smith's answer the end of the conversation. In certain prior cases, the appellate courts conclude that it could be inferred someone knew or should have known they were being pursue by law enforcement, through minimal visual cues, if they accelerated, weaved out of traffic or physically acted in some manner that is consistent with someone who is aware of the police pursuing them to some degree.

This means you will need to assess the specific facts of your case to truly know what your best defenses are. That said, if the evidence unequivocally states that there were no lights or sirens, you have a VERY strong and defensible case that should likely be pushed to trial.