After gone thru all the info above... i think my car got some weird technical problem or wad... Everyone says their car can go 350 - 400km per full tank but mine was 488km/full tank until last bar. When i first got my car, the car could reach as high as 500++km on fuel bar until 5000km service, it drops to 480km/ full tank.

The worst thing i ever seen is... when it reaches 98-99km, it drops 1st bar when all my myvi's fren said different thing and they witness themselves....Please advise. Something is wrong wit the car..