I've noticed this pretty much since I've had the car and was just wondering if it's a normal thing for 4th gens or my fuel sending unit is going bad.

When I fill up the tank it shows a full tank/full bars. It usually takes about 60-70 miles before I lose the first bar. Just recently, the gauge was showing about half a tank so I decided to fill it up to see exactly what the sending unit sees as half. Topping off the tank I realized there was only about a quarter tank. That got me thinking that a half tank is really somewhere on the gauge between the first loss of a bar and half bars.

Is this normal?