In the United States the main car manufacturers have agreed on a common standard for calculating MPG and horsepower.
This means car and truck buyers can rely on the manufacturer’s numbers and compare apples to apples.
But when it comes to trucks and payload and towing no such common standard exists.
This also means that truck manufacturers have as much magic towing dust as they can sprinkle on a pickup.
Here is part 1 of TFL investigates magic towing dust.