fuel milage

Apparently non of the items addressed during the 120k service you just completed on your 2003 Toyota Corolla had degraded to the point where it would affect fuel mileage - that is a good thing. Generally routing maintenance is done in order to replace parts and fluids as they approach the end of there life span but before they begin causing problems. Could you have waited a bit longer to have your 120k service done? Maybe. But the longer you put off the service the greater the chance something will fail causing a breakdown or performance issue.