@SeaFury It is a genuine physical property of petroleum that it takes up slightly more volume when agitated. You absolutely can and will get slightly more if you pump it in a slow, steady stream than if you jam it in as fast as the pump will allow. I’d love someone to do the math on just how much; I don’t think it’s a particularly noticeable amount and I’m certain just driving calmly etc. will have a much bigger effect.

(Note: this is not the fuel station ripping you off: they absolutely DID pump 50 litres or 20 hogsheads or whatever into your tank… and then when it settled, it genuinely BECAME only 49.x liters. It’s a time trade off that is actually unavoidable, though of course in finding the right balance, they are motivated in perhaps a different way than you, the consumer.)