Coming home today , 42 deg F in Elk Grove ,50 in Aurora. Wind E6MPH. 32.0 miles , fcd = 72.6 x .943 = 68.5 MPG. litesong , there is a "bit" of truth in what your mechanic is saying. What I do is measure the width of the rotor , then decide if it needs to be replaced. If it ain't broke, don't fix it. If you really trust your mechanic, he may be right. Of course, what do I know ? I trust almost no one. But I have an honest and competent mechanic. On the Prius, the first brake job was at 118 K miles. We did replace two of the four rotors.