The WardsAuto Fuel Economy Index for July U.S. light-vehicle sales matched the prior-month’s score of 25.3 mpg (9.3 L/100 km). The July rating was 2.3% higher than year-ago and 20.9% above the fourth-quarter 2007 base period.

The average fuel economy of cars sold in the month was 29.7 mpg (7.9 L/100 km), 3.0% above last year. The share of cars in the LV market has seen year-over-year declines for 18 consecutive months. The waning popularity of this relatively efficient vehicle type has slowed the rise in the full market average.

Small cars achieved a record 31.1 mpg (7.6 L/100 km) by a slight increase in share of smaller models in the category. Just behind small cars, midsize cars posted a 1.4% gain to 30.3 mpg (7.8 L/100 km).

The index score of large cars increased 4.8% from July of last year, but has held steady around 23.4 mpg (10.1 L/100 km) over the seven months of 2014.

The segment most improved from last year was luxury cars, jumping 6.1% to an all-time high of 25.8 mpg (9.1 L/100 km). The growth was primarily due to growing demand for diesel, hybrid and plug-in hybrid powertrains.

Light trucks averaged 21.1 mpg (11.2 L/100 km) in July 2014, 2.8% better than 2013. The 7-month average also was 21.1 mpg, as the vehicle type has shown little change this year.

The best-selling segment continued to be CUVs, which regained their high point of 23.2 mpg (10.1 L/100 km). The rating for vans ticked up to a record 20.9 mpg (11.3 L/100 km), while SUVs and pickups repeated June’s outcomes of 17.8 mpg (13.2 L/100 km) and 17.7 mpg (13.3 L/100 km), respectively.

Nissan hit a record 29.3 mpg (8 L/100 km). Significant gains in sales of hybrid and electric vehicles, along with a shift to small cars from utility vehicles, pushed the automaker’s rating up 5.6% from last year.

Increased diesel and EV sales brought BMW’s score to an all-time high of 26.3 mpg (8.9 L/100 km), 12.0% higher than July 2013. The same factors boosted Daimler 9.7% from last year to a record 23.6 mpg (10 L/100 km).

Mitsubishi continued to be the top automaker (excluding EV-only Tesla), maintaining a 30.2 mpg (7.8 L/100 km) rating for the third consecutive month.

The few automakers to show year-over-year declines were Hyundai, Kia, Porsche and Volvo.

The national average gasoline price was $3.69 per gallon in July, down 2.1% from the previous month. This was the first month-to-month drop this year, but sales of alternative-power vehicles grew slightly from June.

Year-to-date, the WardsAuto FEI LV rating was 25.2 mpg (9.3 L/100 km), up 2.2% from the same period last year.