You get more than we do, because here in the US we've got a flexible bladder inside the gas tank. The gas fills the bladder, so it holds less. And in cold weather the bag shrinks, and holds even less. A few people have reported 500 miles. Others, including myself, prefer to play it safe and fill the tank long before it's empty. I don't believe I've ever gone 400 miles. I don't need to.
What's all the talk about a balloon in US tanks. Is that a joke? Here in the UK no balloons. I get 65-66 mpg (imperial gallon - not US remember US gallons are a little less). I used to drive a Golf 1.9 TDI (diesel) and got almost the same mpg but - of course - only by burning diesel with emissions containing particulates with sulphur greater and carbon 140g/km.
I almost always get over 600 miles on a tank. On Thursday I filled up at 597 but was only able to get in 10 gallons. My last bar was not yet flashing and I've gone over 100 miles a few times with a flashing bar. I get in the mid to high fifties on almost all my tanks to date except the very first ones. I have 6000 miles on the car.