On May 15, 2013, two new pieces of legislation to lower financial barriers to using plug-in electric vehicles (PEVs) were passed into law in Colorado by Governor John Hickenlooper. Financial incentives play an important role in keeping PEVs competitive in the automobile market.
House Bill 1247 , called the Innovative Motor Vehicle Income Tax Credit, secures state tax credits up to $6000 for electric vehicle purchasers or lessees until 2021, which would have otherwise expired in 2015. The bill specifically covers any EV that can be recharged from external sources, including plug-in hybrids. The bill also covers vehicles that are converted into PEVs, which are eligible for a tax incentive of $7500. This law will take effect in January 2014.
House Bill 1110 , called the Special Fuel Tax & Electric Vehicle Fee, establishes a flat, annual fee of $50 for the registration of each plug-in electric vehicle. Sixty percent of the fee replaces the revenue not collected from gasoline taxes and goes toward road and highway maintenance, while the other forty percent funds electric vehicle infrastructure such as charging stations. Colorado’s PEV fee as established by HB 1100 is low compared to those considered by other states, which are around $100  or calculated based on mileage  and do not fund PEV infrastructure. This law will take effect in January 2014.
According to Denver Clean Cities , as of July 2012, there were almost 1,300 registered PEVs and around 70 charging public charging stations in the state. However, this number is likely to grow because Colorado is relatively generous with policies supporting electric vehicles .
According to one source, Colorado is the leading state in the region when it comes to PEV policy. A state government report card  from Southwest Energy Efficiency Project (SWEEP) awarded Colorado with a grade of “A-” for its twelve policies that support electric vehicle adoption, including the two laws mentioned above. Colorado does not fare quite as well as California, however, which would earn an “A+” under SWEEP’s methodology because of its major commitment to install fast-charging stations along highway corridors and for 15% of cars sold in the state by 2025 to be plug-in electric vehicles.
For more information:
C2ES: Common Concerns about EV Policy 
C2ES: PEV State of Play  and PEV Literature Review 
C2ES: Powering More Travel with Electricity  Map
C2ES: PEV Dialogue 
plugincars: Colorado Extends $6,000 Plug-in Vehicle Credit Through 2021