You can check for brake drag by taking your car out for a drive and then feeling the brake temperatures. Brake drag will be hot to the touch.
Not sure on the O2 sensors but I suspect if they're bad you'll get a code.
Run your tires anywhere between the door placard and the max sidewall. Measure PSI cold. Find the sweet spot for performance & comfort for you and keep them there. The overall change in MPG isn't that much going from door placard to max sidewall PSI.
Not sure on the O2 sensors but I suspect if they're bad you'll get a code.
Run your tires anywhere between the door placard and the max sidewall. Measure PSI cold. Find the sweet spot for performance & comfort for you and keep them there. The overall change in MPG isn't that much going from door placard to max sidewall PSI.