The speed limit may be 70 miles per hour on I-96. But Giles Brereton chooses to drive well below that despite reactions from other drivers.

"I'm used to mean faces," Brereton said.

Brereton is a professor of mechanical engineering at MSU. He said if gas prices have pinched your budget, you might want to think about taking your foot off the accelerator.

"You will go the most miles with the most gas is you go 55 on the freeway," he said.

Wind resistance increases the faster you go and he said you'll get about 10 percent fewer miles per gallon with every few miles you go above 55.

"More of the dollars you spend on gas, will be spent overcoming wind resistance," Brereton said.

With professor Brereton's help we devised an experiment to see if driving 55 actually makes a difference. We picked the same stretch of road. The first time we drove it 55 miles per hour and the second time we drove it 75 miles per hour.

We drove the six miles on I-96 between Cedar Street and Okemos Road. The average miles per gallon was cleared and cruise control was set. The results? Driving 75 miles per hour we averaged seventeen miles per gallon. Although we got some mean faces of our own driving 55 mph, we averaged 26 miles per gallon.

"It's varies from vehicle to vehicle due to aerodynamics, but it's a good general guide," Brereton said.