M35H Fuel Gauge Issues

[elansam]

2012 M35H
There's an issue I've had since I bought the car. I've just had the car for about a month now and only has 800miles. Every time the gas tank reads 1/4, it only takes 10-11 gallons to fill up to max. I know the tank has a 17.8 gallon capacity. Took it in to the dealer and they replaced fuel pump, sender unit etc. Now after that the issue got somewhat better however still not entirely resolved.
Has anyone seen/heard about a similar issue?