tips an article about a research paper from an MIT economist that attempts to explain why technological advances in fuel efficiency haven't led to substantially better gas mileage for the average driver
"Thus if Americans today were driving cars of the same size and power that were typical in 1980, the country’s fleet of autos would have jumped from an average of about 23 miles per gallon (mpg) to roughly 37 mpg, well above the current average of around 27 mpg. Instead, Knittel says, 'Most of that technological progress has gone into [compensating for] weight and horsepower.' ... Indeed, Knittel asserts, given consumer preferences in autos, larger changes in fleet-wide gas mileage will occur only when policies change, too. 'It’s the policymakers’ responsibility to create a structure that leads to these technologies being put toward fuel economy,' he says. Among environmental policy analysts, the notion of a surcharge on fuel is widely supported. 'I think 98 percent of economists would say that we need higher gas taxes,' Knittel says."