milage

Has the vehicle been tune-up? Along with a fuel system cleaning?

My car did this twice. The first time it was when the local gas station switched to using gas with ethanol added. I switched gas and the mileage returned. The second time was probably multiple factors. It was still running fine. I took it in for a minor tune-up, changed the air filter, put some injector cleaner in the gas and got new tires and the mileage then was better than it had ever been