“It would take tremendous speed or force to throw one nearly half the length of a football field.”
Actually, it would not take any additional force at all, because of a little something called “conservation of momentum”. If the engine somehow broke free of the vehicle it was mounted on, it would continue at the vehicle’s rate of speed until friction brought it to a stop.
What do you mean somehow? Don't you know this is a feature designed to save a driver and take out a sidewalk cafe or line of schoolchildren?