Have read some of the previous reviews and it is a shame that they feel how they do - I know everyone experiences things differently and all reviews should be taken as individual cases.
To that end, we had a wonderful experience with Sixt - the reception is only a minute or so from the main terminal and the staff were welcoming. Whilst having to converse in english (my apologies, Jeg skal prøve å lære meg litt norsk), all details were explained clearly and even included details about a small amount of prior damage to the vehicle on one wheel rim.
Included in the explanation (and part of the document you sign) was the AutoPass fee and that the deposit would be refunded on return with a deduction for AutoPass and any incurred tolls (which is most major highways) - and, in our case, a sliding scale of fees dependant on what state of charge the vehicle returned with (there is an Eviny rapid-charge station about 1km away at Hellsenteret if needed prior to return).
Whilst not under Sixt control, signage out and back in for rental return at the airport is great - much better than some previous experiences hiring in the US and europe.
Will we use Sixt again - definitely.