New cars in April averaged 25.2 miles per gallon, which marked a slight decline from from 25.4 mpg in March and was 0.6 mpg less than last August's peak of 25.8 mpg. Through the first seven months of the 2015 model year, fuel efficiency is even with a year earlier at 25.3 mpg.
That decrease is pretty consistent with US new-car sales patterns in recent months, which reflect a drop in love of hybrids, plug-ins and diesels. Last month, US green-car sales fell 20 percent from a year earlier to about 43,000 units. And even with only plug-in vehicles sales broken out, the numbers were still down about four percent to almost 8,200 units.