My V8 has never shown anything much higher than 300 miles remaining in the 14 years I’ve owned it. Nowhere near 400 miles, ever.
Even when all highway, I’m lucky to get over 300 miles per tank (going over 70, usually). I usually also fill up all the way to the filler cap, sometimes 2 more gallons after the filler stops. I’ve had 23+ gallon fill-ups before.
I’ve never driven in a way that would maximize mileage, e.g., trying to see how many miles I could squeeze out of a full tank. I’m not a lead foot, just not light on the gas.