Did you mean 13-16 kW? Where did you get those numbers? Do you have a link?

EPA is much lower:

UDDS ~3200W

Highway ~8400W

FTP ~5300W

There's still other correction factors that changes this, but from the pure test numbers, the cycles don't actually consume that much power on average, so a continuous power draw may be more significant than you may think.

Tesla lowers Model 3 range estimates in Europe due to extra power consumption of AMD Ryzen processor
Just some quick math:

EPA shows max usable is 82kWh for Model 3 LR:

Previous WLTP range was 614 km.

Tesla Model 3 Long Range Dual Motor
WLTP cycle used would be Class 3B (larger vehicles with Vmax greater than 120km/h) and average speed there is 23266m/1800s = 12.93 m/s = 46.55 km/h

Emission Test Cycles: WLTC
That means the test would take 614km/(46.55km/h) = 13.2 hours

82kWh/13.2h = 6.2 kW

That matches the ball park of the consumption on the EPA test, so makes sense.

And to finish the math, 12km (claimed difference)/614km is 2%, 2% of 6.2kW is around 120W. That's more than from the Ryzen APU alone, but if you add in the Navi GPU (assuming it's true it's discrete, which from what I can find there is no analog in the Atom computers) it's not out of the realm of possibility.