[Christok]

My ex brother in law used to drive 2.5 hours in the morning to work and 2.5 hours at night to get home and did this for about 5 years. (over 300 miles per day mostly highway split between 65 MPH and 50 MPH) In the five year period he went through 3 cars but kept extensive records of his gas mileage. He calculated that his cars started getting their best gas mileage around 50,000 miles. The products were GM and were bought new or with very little mileage on them. May not give you the answer with respect to the Camaro but opens eyes with respect to when cars in general start to get their best mileage.