The sun is that far away?
The slogan for this tanning studio says
Yes indeed. The Norwegian mil is equal to ten kilometers. Presumably, the competitor to which they refer is probably the Sun — which is roughly 150 million kilometers away, or about 93 million imperial miles.
The UltraSun chain doesn't appear to be active in any English-speaking country, which makes the use of imperial units in Norwegian all the more odd, since it can't be attributed simply to a careless translation of some English slogan.