Do they open the track to the public? If so how much?

I have not heard of "track renting" there....although it might be available to "a select few" $$$

Regular event tickets go for $14. Special events are $17, and $19 for touring series races. Pit admittance costs $35 if you are not a NASCAR member. The racing season runs April-October ish, save a handful of special events. If you're asking as a racer, there us more information on their website, coloradospeedway.com.