I have bought a 2nd hand Gs500E - 1997. All the literature I can find says it has a 17 + 3 litre tank. Milage calculations show it using 20 kilometres to the litre and should therefore be getting around 340km before switching to reserve. Why then am I consistently reaching down with my left hand at 240 km and only putting in about 12 litres. What gives? Anyone any clues? I am suspecting a 12 + 3 litre tank but without draining it into a bucket I cant be sure.