JDM tanks are 70 litre. The most i've ever got in my JDM tank is 73.5 litres, and my MPG pod had been flashing as empty for close to 40 miles (long story, on the way back from the nurburgring, late for the ferry, took a wrong turning and had to go 17 miles toward paris whilst on empty )
So that suggests to me you've got a UK tank