I came across this post in an old thread and it describes exactly what's happening with my 96 Vienta. Toyota fuel gauges are notoriously unreliable in older cars and non-linear in some newer ones, especially 90s ones. Going off the gauge, my '97 Corolla will do 300km on the first half of a tank, ~100km on the next quarter, and then struggle to get more than 50km on the last quarter before the fuel light starts coming on. I'm trying to figure out how much fuel is left when the warning light comes on because last time it happened I put in 30 litres which sent the gauge up to mid-way between 1/2 and 3/4 full. Tank is 70 litres so 30 should have taken it to below half not way over. Anyone know what's really going on?