The Texas Transportation Commission could take up the proposed change, which would apply to Interstate 10 and Interstate 20 in West Texas, when it meets in Austin next week.
Carlos Lopez, director of traffic operations for the department, said a survey of both interstates found that 85 percent of motorists were driving up to 79 mph.
"If people begin to think that the number on the sign is unreasonable, then they won’t respect it," Lopez said. "Just putting up a lower number on the highway isn’t going to slow down traffic."
Increasing the speed limit "will have a perverse reaction," said Peter Iwanowicz, director of environmental health at the American Lung Association. "Increasing the speed limit will increase fuel use."
U.S. Department of Energy studies show gas mileage usually decreases rapidly at speeds above 60 mph. The agency’s Web site says that motorists generally pay an additional 20 cents per gallon of gas for each 5 mph they drive over 60.