Any legislative effort to establish a vehicle-use tax to offset diminishing gasoline tax revenues faces an obstacle course with caution lights blinking from all directions. So, it would be easy to line up reasons to oppose a bill, expected to be introduced in the 2013 Legislature, that would impose a per-mile tax on vehicles getting at least 55 mpg. But, it also would be easy to argue against any alternative suggestion. That’s the problem with change; it’s uncomfortable. In this case, it’s better to focus on the reasons to move forward. For the most part, even automobile manufacturers and anti-tax …