WardsAuto Fuel Economy Index fell for the second consecutive month after registering a record-high 24.1 mpg (9.74 L/100 km) rating in March.

New cars and light trucks sold in May combined for a 23.8 mpg (9.9 L/100 km) rating, marking a 1.0% drop from April’s 24.0 mpg (9.8 L/100 km).

May’s decline came as the overall seasonally adjusted annual rate fell to a 5-month low of 13.7 million units, well below the year-to-date average SAAR of 14.3 million, and gasoline prices dropped for the first time in five months, to a 3-month low of $3.79 a gallon.

The reduction in adjusted sales volume and fuel prices corresponded with an increase in light-truck market share, causing the bulk of the Index’s downward movement.
Cars made up 50.6% of all light-vehicle deliveries in May, down from 52.5% in April, and earned an index rating of 27.1 mpg (8.7 L/100 km) compared with the light-truck rating of 20 mpg (12 L/100 km).

Small cars accounted for 19.9% of all LV sales, which was even with April, while scoring a 29.6 mpg (7.9 L/100 km) rating. However, Midsize, Large and Luxury Cars all lost share from April to May.

Midsize cars fell to the No.2 segment spot with 22.3% of sales, averaging 26.7 mpg (8.8 L/100 km), while CUVs climbed to No.1 for the first time in four months with 23.6% of the market, and a comparatively lower 22.2 mpg (11 L/100 km) on the Index.

The May fuel-economy score was the industry’s fourth-highest ever and represented a 13.5% improvement over the Index’s base rating of 20.9 mpg (11.2 L/100 km) established in fourth-quarter 2007.

Toyota remained atop the WardsAuto FEI in Maywith a 27.3 mpg (8.6 L/100 km), but the score was more than a point below the auto maker’s record April rating of 28.5 mpg (8.2 L/100 km).

Toyota’s drop came with a slight tapering off of sales of the Prius hybrid range, which also corresponded with an industry-wide drop in hybrid- and electric-vehicle market share.

Asian auto makers combined for an industry-leading 26.1 mpg (9 l/100 km) in May, followed by the European brands’ 23 mpg (10 L/100 km) and the Detroit Three’s 21.3 mpg (11 L/100 km).

Some 71% of vehicles sold had ratings of 20 mpg (11.8 L/100 km) or more on WardsAuto FEI last month, compared with 66.9% year-ago.

Domestic-built vehicles registered 22.9 mpg (10 L/100 km) for the second straight month, while imported cars and trucks fell 2.7% from their record April with a collective rating of 26.8 mpg (8.5 L/100 km).

The industry rating for the year’s first five months was 23.9 mpg (9.8 L/100 km), a 4.4% gain over like-2011.

jsousanis@wardsauto.com