Each month, the University of Michigan's Transportation Research Institute (UMTRI) tracks sales-weighted fuel economy ratings of new cars purchased in the US. Its data goes back to October 2007, and there have been solid gains since it began. Last month bucked that trend, though, and as a result we've seen the average fall once again.
Thankfully, it's not that big of a dip. May 2016's value was 25.4 miles per gallon, and June's is but 25.3. It's not necessarily surprising, either -- over the last year, we've seen the graph take a bit of a downturn as gas became cheaper and more Americans jumped on the crossover bandwagon. Sadly, that bandwagon contains no actual wagons, because we refuse to buy them for whatever silly reason.
The chart peaked in August 2014, when average economy was 25.8 mpg. That's also when gas was outrageously expensive, with the national average around $3.70 per gallon. As the price has gone down, buyers have moved away from more fuel-efficient vehicles.
We've been in a sort of holding pattern for about a year now, with average fuel economy rising and falling several times. It's likely that the 2016 model year average will hold steady, as it has done for the two model years before that. Unless gas prices shoot back into the ionosphere, we're likely to see stagnation until automakers start ramping up fleet fuel economy ahead of tightening Corporate Average Fuel Economy (CAFE) regulations, which is set to happen in the next decade.