Fuel tax vs. Carbon Tax

They are often argued as if identical. A fuel tax is a tax on inputs. A carbon tax is a tax on outputs. If engine efficiency doubles, carbon output halves. (Which would theoretically lead to fuel consumption halving, and hence the same effect).

But it's an essential political division: voters hate paying for necessary life inputs: food, housing, gasoline. Raise the price of any of those in a big way, and you've got a riot on your hands. (See: Paris). But when you tax outputs, its simply a 'cost of doing business'. The tax is hidden. And what is hidden is often forgotten. (Viz: Mortgage interest subsidies). A carbon emission tax also syncs with the 'polluter pays' principle.

Rather than taxing coal (and all those hardworking coal miners), or electricity, tax power plants at the smoke-stack. The cost of the tax is hidden from consumers--they can't tell if the powerplant is passing on an increase in cost, or just trying to ring some more money out of consumers. 

Tax cars at the smoke-stack as well, at the tail-pipe: Come in for safety and emissions, and get a bill for your vehicle emissions. Gas tax goes away (an equity plus) while the worst (most-polluting) cars are pulled from operation.