Every now and then I hear about someone buying a brand new Prius, then driving the thing a hundred miles home or more. Call me straight, call me square or whatever, but in the owner's manual .... 'for the first 600 miles, avoid driving at a constant speed for long periods of time. ' I'm quite sure new engines like varying loads like suburban driving when new. Hitting the highway for a long stretch seems to break one of Toyota's break-in rules. What say you? btw, I'm avoiding any long, cruise control type highway stretches for at least 600 mi.