The average fuel economy of light vehicles sold in the U.S. in the first six months of 2014 was 25.2 mpg (9.3 L/100 km), according to the WardsAuto Fuel Economy Index (WFEI). The rating is 2.2% above the same period of 2013, even though market share of heavier segments increased.

The average rating for cars over the first half of this year grew 2.6% to 29.3 mpg (8 L/100 km). Large cars were the most improved car segment, up 3.5% to 22.9 mpg (10.3 L/100 km), and the only car segment to gain market share. Midsize cars showed a gain just behind large cars, growing 3.2% to 29.7 mpg (7.9 L/100 km), but had the largest drop in popularity of all segments.

The rating for small cars rose 2.6% to 30.9 mpg (7.6 L/100 km). Luxury-car sales came in at 25.1 mpg (9.4 L/100 km), up 2.3%.

Light trucks averaged 21.1 mpg (11.2 L/100 km) through June, 3.2% higher than year-ago. The most popular segment, CUVs, scored 23.2 mpg (10.2 L/100 km) on the index and accounted for over 25% of light-vehicle sales. Pickups showed the biggest gain in fuel economy, up 5.7%, but remained the lowest-scoring group at 17.7 mpg (13.3 L/100 km).

SUVs were the least-improved segment, growing 1.3% to 17.9 mpg (13.1 L/100 km). The score for vans rose 1.9% to 20.8 mpg (11.3 L/100 km).

Domestically built models, over 75% of the market, averaged 24.6 mpg (9.6 L/100 km), up 2.4%. The rating of imported light vehicles was up 1.1% to 27.5 mpg (8.6 L/100 km).

Mitsubishi was the top automaker (excluding electric-only Tesla) with a 29.6 mpg (7.9 L/100 km) 6-month average and the only company to score a monthly rating above 30 mpg (7.8 L/100 km) on the WFEI.

Just behind Mitsubishi was Mazda at 29.5 mpg (8.0 L/100 km). Mazda is one of the most improved automakers, up 11.7% from last year.

Jaguar Land Rover posted the biggest gain from 2013, jumping 12.7% to 19.4 mpg (12.1 L/100 km). JLR was the only automaker still below 20 mpg (11.8 L/100 km).

The only automakers to see year-over-year declines were Hyundai and Volvo, which both shifted toward heavier, less fuel-efficient models.

National average fuel prices were slightly lower than last year. The 2014 6-month average for gasoline was $3.61 a gallon, down 1% from $3.65 in 2013. This year, month-to-month increases haven’t surpassed 5%, allowing consumers to more easily adjust to higher fuel costs than in prior years.

eberger@wardsauto.com