Determines a ballpark estimate of horsepower
The resulting number is the engine horsepower at the flywheel which is the measurement car manufacturers claim. There is a loss of horsepower through drivetrain. Many sources say that you can expect at least a 15% loss of engine horsepower with front and rear wheel drive cars, more for all wheel drive vehicles. Efficiency is a major role in reducing drivetrain loss, many times what improves gas mileage also improves wheel horsepower through mechanical efficiency.