The learning curve for policy makers is steep (ignore market forces at your own risk):
Automakers are unlikely to hit the 54.5 mile per gallon average fuel efficiency level that President Obama trumpeted for years, federal officials said Monday.
Blaming it on higher-than-expected sales of large vehicles like SUVs, the Environmental Protection Agency (EPA) and Department of Transportation (DOT) said automakers will probably miss the mark that the Obama administration touted in its historic 2012 regulation regarding vehicle fuel economy and greenhouse gas emissions.
The forecast was part of a 1,000 page draft technical report from the two agencies, the first step in evaluating whether to strengthen the efficiency rules for the 2022 to 2025 model-year period.
The report itself does not constitute a decision to tighten the rules or even a proposal to do so, but the finalized version of it is likely to weigh heavily on the evaluation.
Speaking with reporters about the projections, Obama administration officials stressed that despite the high profile of the 54.5 figure, it was never a standard in and of itself.
“54.5 isn’t a standard, never was a standard and isn’t a standard now. 54.5 is what we predicted, in 2012, the fleet-wide average could get to, based on assumptions that were live back then about the mix of the fleet,” a senior administration official said.
“That depended a lot on a variety of factors, including gasoline prices,” the official said. “We’re recognizing the fact that gasoline prices are lower now.”
I haven't read the 1000 page draft technical report so I wonder how it dealt with the uncertainty about gas prices? It is very difficult to foresee the technological shock of fracking but, still, a 54.5 miles per gallon goal is dependent on the market for gasoline and any such target should have a very wide confidence interval. Needless to say, it would be much more straightforward to increase miles per gallon with a higher gas tax.