No mechanic for that was created. I think it fell into the "Some burn quick, some last forever, most have fuel until the plot says otherwise" handwavium form. I mean, if enough people *want* a dedicated power factor/fuel efficiency matrix, I could grab Aaron and ask him to do Math, but the question would be, "Is it worth it?"
Because I'm down, but most people aren't happy with fiddling with, say, what percentage of their gastank is available after driving from Dante's to Council Island to the Redmond Barrens.