The WardsAuto Fuel Economy Index shows the average fuel economy of light vehicles sold in the U.S. in September was 25.4 mpg (9.2 L/100 km), down 0.3% from year-ago.
The national average gasoline price was $2.761, 10.7% higher than in August and 18.7% above year-ago.
Share of standard gasoline models fell to 96.2% from 96.4% in same-month 2016. Share of all alternative power types increased.
Cars sold in the month averaged 30.1 mpg (7.8 L/100 km), down 0.8% from year-ago. Domestically built cars slipped 0.4%, while imports rated 1.9% behind year-ago.
All car segments show declines from prior-year. Midsize cars showed the biggest drop, 1.3%.
Light trucks reached a record high market share and scored 22.7 mpg (10.4 L/100 km) on the index, a 2.5% gain on prior-year. The average rating for domestics increased 2.3%, and imported models improved 2.1%.
CUVs reached a best-ever 25.3 mpg (9.3 L/100 km) with a 3.1% gain from September 2016. Penetration of electrics and hybrids in the segment rose from year-ago.
SUVs were the only light-truck segment to come in behind year-ago, declining 0.7% to 18.6 mpg (12.6 L/100 km).
Volvo’s index score rose 1.4% to a record-high 24.1 mpg (9.8 L/100 km), boosted in large part by sales of plug-in hybrids.
Kia recorded the biggest year-over-year improvement among tracked companies in September, jumping 5.4% with a higher share of hybrids.
Volkswagen showed the greatest decline from prior-year, down 10.1%, due to decline in electric and hybrid vehicle sales, along with a shift from midsize cars to CUVs.
Honda was the highest rated automaker (excluding electric-only Tesla) at 29.1 mpg (8.1 L/100 km). Porsche had the lowest score, 20.4 mpg (11.5 L/100 km).
The industrywide index rating for the first nine months of 2017 was 25.4 mpg (9.2 L/100 km), up 0.1% from same-period 2016.