> I'd love to hear about what you think is "untrustworthy" about converting from kilometres to miles so the audience can visualize the distance. 1000 km = 621 miles, this is a fact.

1000km is not an exact figure. It’s rounded, probably up. Somewhere between 900km and 1100km. Likely closer to 999km than 1099 because they’d want to publish the biggest number they can reasonably claim. So you can assume the real range is between 900km and 999km.

The correct translation to miles would be “600mi”. Because 621 invents precision that wasn’t there in the original figure.