Oregon government officials continue to consider a per-mileage tax for plug-in and highly fuel efficient vehicles. The reason? To boost road-improvement funds in one of the country's most progressive states, the Register-Guard from Eugene, OR, reports.

Earlier this week, state officials held the first public hearing for House Bill 2453, which would institute a per-mile fee for model year 2015 (and later) vehicles that get at least 55 miles per gallon. The fee may be about a cent and a half per mile, which would equal about $230 annually for a plug-in vehicle owner who drives 15,000 miles.

The bill is being considered because gas taxes fund about 60 percent of Oregon's road improvements, and the state is one of the more advanced when it comes to the adoption of plug-in vehicles. Oregon, which accounts for about 1.3 percent of the US population, is home to almost six percent of the country's publicly accessible EV charging stations, according to US Department of Energy figures.

Earlier this year, Oregon proposing a per-mile tax measure on 55 mpg-plus vehicles. The state had previously considered applying a 1.2-cent-per-mile tax, but that proposal was rejected in 2011. Meanwhile, Washington State started adding $100 to annual registration fees for electric vehicle owners. Texas is among other states considering extra registration fees for plug-in vehicle drivers.