I really wouldn't trust the accuracy of any ebike's power rating; and of course it depends on whether that is "watts required" or "watts delivered to the wheel".
I was passed by a guy on a mountain bike once, so I started trying to catch up. I noticed it seemed really hard, until finally I was on the edge of absolutely killing myself to try to catch him.
But I finally did, and then we both had to stop for a light, and I noticed he had an e-motor in his rear hub. So I started laughing and asking him about it. He said it was rated at 500 watts.
I can very rarely produce 500 Watts for about a minute!
There's also the issue of whether he was maxing out the throttle (or PAS). You don't slam the gas pedal to max hp revs when driving your car all the time do you?
It's also worth noting that every thing else has to be rated to deliver power including the batteries and motor controller. And if you want to be technical, bicycles also have a drive train efficiency loss, and tires losses, so what you really want is dynamo power, or power at the wheel (not hub). So even then leg watts aren't quite the same as speed watts.
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