The truth about GROSS hp vs NET hp
The examples in this article hasn’t aged well as 99.99% of automotive specs sheets nowadays only show net horsepower ratings, but it still makes for interesting reading, especially as there are still a couple of hold-outs advertising gross horsepower in this day and age. We led the way back then in exposing this practice.
I just got the press release for the new 2008 Chevy Avalanche, to be launched mid-October, claiming their 5.3-litre V8 to have 355 hp. I also read a review in Wheels magazine where the writer assumes the Tahoe has 355 hp, and that the Murano has 265 hp. And then there is another review on AutoMiddleEast where they use Ford ME’s explanation that net hp means power at the driven wheels. Also, a lot of people assume that since Nissan ME claims the Infiniti G35 has 330 hp locally, the American-market models have more catalytic converters or something to reduce their power to 306 hp. They are all WRONG!
I didn’t spend four years in journalism college, so I am not a “professional” writer. I did spend more years than that studying engineering in college. But that’s not why I know the difference between GROSS power and NET power. I know it because I simply looked it up on the internet. Back in the last century.
Before 1972, most American automakers rated their engines in gross hp, under Society of Automotive Engineers (SAE) standards. Gross hp was measured using a test engine running on a stand without pumps, extra fans or anything else installed. It is the maximum theoretical value of power, and nowhere near what a car gets on the road. Gross hp figures were so often manipulated by car manufacturers and marketers that the SAE decided to adopt a new standard of power that took accessories into account.
The SAE chose to use net hp ratings, which measures engine power at the flywheel, but still not counting drivetrain losses. It does take into account all accessories, intake and exhaust systems. By 1972, most carmakers quoted power exclusively in net hp. Net ratings are more accurate than higher gross ratings. Many people incorrectly report net hp as being measured at the drive wheels. They confuse net hp with wheel hp, which is even lower. Wheel hp is what you get when power at the drive wheels is measured using a dyno. The worldwide standard remains net hp however (whether under American SAE, European ECE, German DIN or Japanese JIS rules). The same story applies to all torque ratings too.
The Middle East seems to be the only market in the world which reports power in gross figures and gets away with it due to the ignorance of the traditional media. Kudos to Germans for sticking to the net power standard here.
Change is happening with the others though. While the Avalanche press release is an oversight, General Motors, Nissan, Toyota and others do mention “gross hp” in most advertising materials nowadays, though the public doesn’t know the difference. So people continue to assume that the 158 net hp Toyota Camry is a lot less powerful than the 187 gross hp Honda Accord. Chevy and Toyota even jump between net and gross for different models, as do many of the “comprehensive” car buyer guides in most local magazines. What a mess.
We exclusively list NET hp for all cars on this website (except maybe for Chery, but give them a break).