The checkerboard pattern of constantly changing electric-car incentives and fees among the 50 American states often baffles outsiders.
And as states go, Colorado has a mixed record.
But its electric-car incentive turns out to have a quirk not shared by any other state, as far as we can determine.
DON'T MISS: Want $42K Off A New Tesla Roadster? Call Your Colorado Cousin (Oct 2009)
That is the eligibility of its electric-car purchase tax credit not just to new cars, but also to used cars on which the credit hasn't previously been claimed.
That largely applies to electric cars imported from other outside Colorado.
That state's electric-car purchase tax credit lets taxpayers claim a credit for 75 percent of the premium over a comparable gasoline car, up to a maximum of $6,000, for purchasing a battery-electric or plug-in hybrid vehicle.
Old cabin near Twin Lakes, along Colorado's Top of the Rockies Scenic Byway
According to a Colorado electric-car advocate who asked to remain anonymous, a Colorado resident can claim that credit on any electric car whose Vehicle Identification Number (VIN) hasn't previously been submitted to the program.
That means that, in theory, a Colorado resident could travel to California to buy a 2011 Nissan Leaf that had been registered there for three years--the time required to claim that state's electric-car purchase rebate.
Our source says that the buyer could then truck it to Colorado, register it as a used car, and legally claim that state's tax credit on the year's tax return.
ALSO SEE: Ranking SW States On Electric-Car Support: CO Best, WY Worst (May 2013)
That quirk aside, two years ago, Colorado was rated the most electric car-friendly of six Southwestern states studied by the Southwest Energy Efficiency Project (SWEEP).
On the other hand, Colorado is one of several states that have instituted a special registration fee on electric cars to compensate for the gasoline taxes they don't pay.
Tesla Roadster recharging at Denver International Airport, from SolarDave blog
But in Colorado, it's among the lowest, at just $50 per year.
Better yet, $20 of each car's annual fee goes to the state's Electric Vehicle Grant Fund, which pays for public charging stations and other infrastructure.
Back on the minus side of the roster, at the behest of the Colorado Automobile Dealers Association, the state was one of the earliest to change its franchise laws to prohibit Tesla Motors from opening additional Tesla Stores within the state.
That took place back in March 2010, as the association's president Tim Jackson proudly related to Green Car Reports during an interview we published in October 2012.
MORE: Why Electric-Car Owners Should Be Happy For New Colorado Tax (May 2013)
If the goal of incentives that encourage electric-car purchases is to get more of the cars on the road, then presumably the Colorado law will do exactly that.
A used electric car imported from another state presumably substitutes for the gasoline car that would otherwise have been purchased (though, admittedly, that car is hardly likely to be exported in exchange).
Still, it begs the question: Why don't states provide incentives for buying used electric cars as well?