I know where @Ackmaniac is stuck. Let’s see if I can explain it better…
Basics: Power §= ViAi = W Energy (E)= integral(ViAi*dt)= Wh
Total Energy content varies with how hard you push, push 1A on a 10A cell and you get ~12.6Wh of energy. Push 7A on that same cell and your total energy drops to ~10.75Wh. If you have a 40cell battery in ANY configuration (1s40p or 10s4p don’t matter) and you’re drawing an average of 1000W, you just lost at the very least 14.7% of your range this is because your performance differs when you get on the board to halfway through your ride to towards the end of your ride, to draw 1000W at 3.8V/cell it takes 6.6A/cell, at 50% and 3.44V/cell it takes 7.27A/cell and towards the tail end at 3.0V/cell it takes 8.33A/cell So you can see how 14.7% is lost is really conservative.
Now if you have a lipo with the same rated capacity at the same nominal voltage and a 60c discharge rating your voltage sag is non existent and your discharge curve is pretty flat which means your battery energy doesn’t change regardless of how much power you draw.
So yes, hills do reduce range. Same as a car.