The University of Michigan's monthly fuel economy index for August indicates American opted for more fuel-efficient vehicles during August in response to an increase in fuel prices.

The average fuel economy of new vehicles sold in the U.S. in August was 23.8 miles per gallon --up 0.2 mpg from July, and up 3.7 mpg or 18 percent  from October 2007, according to the University of Michigan's Eco-Driving Index. "The improvement from July to August most likely reflects the increased price of gasoline," U-M analysts noted.

   August sales figures showed that pickup trucks sales also increased during August. But while pickup trucks remain a key tool in American economic life, fuel-economy is now a key factor in consumers ultimate choice. The U-M index, despite a dip earlier in the summer when the price of gasoline dropped in many parts of the country, has continued to creep upward for most of the year, suggesting consumers are looking for greater fuel efficiency in the face of rising fuel costs.

 In addition, manufacturers such as Hyundai and Ford have promoted the efficiency of their new vehicles, touching off a what once Honda executive described recently as a 'fuel-economy arms race." Several manufacturers now offer vehicles that get better than 40 miles per gallon, a figure unheard of as recently as three years ago.

 The U-M Eco-Driving Index (EDI)--an index also indicates the average monthly emissions generated by an individual U.S. driver--stood at 0.82 in June (unchanged from May but an improvement of 18 percent since October 2007).  The EDI takes into account both vehicle fuel economy and distance drivenI.

 The average sales-weighted fuel economy was calculated from the monthly sales of individual models of light-duty vehiclesand the combined city/highway fuel-economy ratings published in the EPA Fuel Economy Guide for the respective models. For both monthly and model year averages, sales-weighted means were calculated. By Joseph Szczesny