Various Shinkansen lines average that much or higher for long stretches. To be fair, there isn't a 1000km line in Japan, but ~500km at those speeds should indic

Various Shinkansen lines average that much or higher for long stretches. To be fair, there isn't a 1000km line in Japan, but ~500km at those speeds should indicate that it's possible. Sanyo runs at near maximum operating speed (300km/h) for most of its >500km run.