The Shelby GT500 has joined the ranks of the new Toyota Supra and BMW M5 as producing more horsepower than the manufacturer has advertised. YouTube channel Speed Phenom did a dyno test of the new top model Mustang and discovered that it was putting out at least 50 more ponies than is on the spec sheet.

The number is determined by taking the 'at the wheels' number and applying the general 15% loss that happens form the flywheel to the rubber.

3 Power Estimates

Companies underselling their power output has a long history in automotive circles and has happened for a number of reasons. In the past it's been used to skirt insurance classifications or meet imposed restrictions. Japanese manufacturers for a time under reported their numbers when they had entered a gentleman's agreement to stop producing risky high power cars.

2 Fast Company

The GT500 has fast company in underselling its power, mostly from BMW and BMW related products. When Car and Driver became convinced that the new Toyota Supra was outperforming its stats they dyno'd their test mule and found it producing 339hp at the wheel, five more than Toyota claimed at the crank. Similarly, the BMW M5 Competition claimed 617hp at the crank but was found to be putting that down at the wheels.

1 Horsepower Estimates

During the dyno test for the GT500 705hp found its way to the wheels. With the power listed for the Shelby hot rod listed at 760hp and the transmission loss, power output should have read closer to 646hp. Previously a C8 Corvette tested higher on the dyno than listed but the culprit was found to be bad calibration. Outside of calibration problems, the difference could be a product of the new dual clutch transmission that may transmit the power more efficiently.