An economics professor at MIT says if cars weighed less and had fewer horsepower, they

According to MIT Professor of Applied Economics, Christopher Knittel, small cars and light trucks could have much higher fuel economy ratings than they do.

In “Automobiles on Steroids,” Knittel says that that stunted growth in fuel economy averages can’t be blamed on slow strides in fuel-efficient technologies. Advances “have barely increased the mileage per gallon that autos actually achieve on the road,” says MITnews. “Because automobiles are bigger and more powerful than they were three decades ago, major innovations in fuel efficiency have only produced minor gains in gas mileage.”

Passenger cars gained about 414 pounds in 26 years. “In 1980, the average weight for passenger cars was 3,041 pounds, but it rose to 3,455 pounds by 2006,” says The New York Times. Some of the weight gain can be blamed on heavy safety equipment, but consumer preference also drives the trend. Americans love their trucks and SUVs, which are far from conservative at the pump, and they want plenty of power to move these vehicles. Automakers produce these vehicles to meet consumer demand, but they also compromise fuel efficiency.

The shift is evident in fuel economy, horsepower and vehicle weight data from 1980 to 2004. “The average fuel economy of the U.S. new passenger automobile fleet increased by less than 6.5 percent, while the average horsepower of new passenger cars increased by 80 percent, and their average curb weight increased by 12 percent,” says the National Bureau of Economic Research. “For light duty trucks, average horsepower has increased by 99 percent and average weight increased by 26 percent over this period. But there's more to this story: in 1980, light truck sales were roughly 20 percent of total passenger vehicles sales -- in 2004, they were over 51 percent.”

Knittel hypothesizes that if today’s vehicles were reduced to 1980 weight, horsepower and torque levels and benefited from new green technologies, the current fleet average of 23 mpg would be 37 mpg.

“Automobiles on Steroids” was published after the U.S. government’s new Corporate Average Fuel Economy (CAFE) standard that requires a fleet average of 54.5 mpg by 2025. According to the National Bureau of Economic Research, Knittel says that if there is “a shift back to the average weight and power seen in 1980, along with a continuation of the trend toward greater fuel efficiency,” the fleet-wide average could be 52 mpg by 2020.

Shopping for a new car? Check out the U.S. News rankings of this year's best cars. Then, look for a great deal on a new car by checking out this month’s best car deals. You can also skip negotiating with a dealer by using our Best Price Program. Also, be sure to follow us on Twitter and Facebook.