This is what it says in the manual (2006 Caravan):
ENGINE BREAK-IN RECOMMENDATIONS:
Drive moderately during the first 300 miles (500km). After the initial 60 miles (100 km), speeds up to 50 or 55 mph ( 80 or 90 km/h) are desirable.
While cruising, brief full-throttle acceleration, within the limits of local traffic laws, contributes to a good break-in. Wide open throttle acceleration in low gear can be detrimental and should be avoided.
I don't know why today's car still needs break-in. I just blindly follow.