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"both a stick of butter and an SUV traveling at 100 mph contain about a kilowatt-hour of energy"

How's that?

The stick of butter is easy: it contains about 800 kilo-calories.

This can be converted to 0.94 kWh: (calories)(joules per calorie)(watts = joules/second)(kw = 1000w)

Kinetic energy is 1/2(v*v^2)

The average SUV weighs about 2000 Kg. That yields about 0.55 KWh. Perhaps the parent used a larger SUV.

It still seems bonkers to me. What if the SUV slowed to a stop, standimg at rest beside the stick of butter. Which represents more potential energy?

Besides the gas in the tank the car has zero potential energy at a stop. All the kinetic energy was lost to heating the brakes.

The parent forgot the 1/2. So more like 140 mph (or a heavier vehicle).