My`98 Mercedes booklet states a break in period for the first one thousand miles.
The magazine Race Car Engineering had a great article on break in periods some ten years ago. It did state that hypoid gears -rear diff- do benefit from a break in period.
Some cars, Ferrari, Lamborghini do or certain models have used test drivers taking new production cars for shake down drives at the factory before shipment. But rapid acceration within a certain rev range is probably less stressful on a new engine than lugging the engine on hills, steady state speeds for extended periods of time and even prolonged idling