Is this conversion a result of fuel economics, or a result economics related to EPA/Evil Environmentalists?
I suspect the latter.
The enviro-weenies are having fits over the construction of a LNG dispensing station in Tacoma Washington (a largish city in Washington state). They don’t care that LNG is better for the environment much less the economy.
Pure NIMBY-ism.
In this specific case, I think not. Fracking has dropped the cost of natgas so much that diesel is simply less economical. And as fracking continues to burgeon and become more efficient, the difference is only going to get larger.