Worth mentioning that a single barrel of oil has a relatively fixed amount of each fuel type (i.e., gasoline, diesel, kerosene, etc). So when tax policy in one

Worth mentioning that a single barrel of oil has a relatively fixed amount of each fuel type (i.e., gasoline, diesel, kerosene, etc). So when tax policy in one place favors one portion of the barrel, the "extra" other fuels have to go /somewhere/. That tax policy in Europe favors diesel it makes it relatively cheaper to buy gasoline in the States (and vice versa). Economies of scale within distribution and manufacturing networks seem to favor one dominant fuel at a time for passenger vehicles.