I check every tank on every rig I fill up with a mph readout and have only ever owned 1 that’s accurate enough to take for what it says, that’s my MB Sprinter. The sprinter, aside from tank one that I didn’t fill has been holding -1.1% - 2.9%, and since tank 3 the biggest error is 2.3% with most tanks within 1%. I’ve never had any other rigs I could do that with, especially my Rams both gas and diesel.
The first 3 tanks on my 22, which should be very similar to your 23, were 2.2, 7.2, and 8.3 % off. The forth tank was -0.6%, followed by a 14.5%, then a 2.8, then a 14.5%… it goes on just like that. Over the time I owned that truck the range was -1.1%-22.8% error. There is a reason they are called a lie-o-meter.
The only way to know what you’re actually getting is to hand calc.