I just read this in Grassroots Motorsports (Vol. 22, Number 8, December 2005) page 23:

"The Society of Automotive Engineers has revised their methods used to measure the net horsepower and torque numbers for new cars. As a result, these new J1349 (Rev 8/04) net calculations may cause 2006 models to appear to show a decrease in power output, even though the engine specifications have not changed. Honda, for example, has already adopted these new specifications; as a result, their new Ridgeline is now rated at 247 horsepower, even though the initial specification stated 255."


Obviously, we need to keep this kind of thing in mind in the future when it comes to classifying cars in IT...