Thanks for the replies Twin Turbo and rukmaldk!
Yes, it's a manual, and I've checked the fuel consumption in outstation rides as well, refueling from several stations.
No, unfortunately, the check engine light doesn't come up ? I think it's either burned out or someone removed it.
Took it to a tune-up yesterday and found out that the scanner port is also not there. Guy looked everywhere under the dash but couldn't find it. Did a manual tune-up anyway, cleaned injectors and intake system and replaced injector filters and plugs. Tune-up guy said there could be a fault with the O2 sensor.
Now I'm thinking the first thing to do is fix the scanner port somehow. It should tell whatever is not working right?