DENVER — Unless you have a turbocharged engine, regular 85 octane fuel may be the most expensive gas purchase you need. But for more miles per gallon, 87 octane may be the better buy than 91 octane fuel.
John Jechura, a professor of practice at the Colorado School of Mines, has logged his gas purchases and mileage since 1989.
“I keep track of whether I’ve got mid-grade, premium or regular,” Jechura said. “I do my mileage calculations and total miles. I have way too much time on my hands.”…