Car enthusiasts: what are the possible reasons for sudden increase in fuel consumptuon of a 10 yr old car?

The car is a 10 yr old Honda. It was averaging 24-25 m/gallon for about 5-6 years and suddenly it has started doing 20-21. Tyres are new. Is not like I have moved to different climate. Driving habits or route has not changed. What could be the possibilities? thanks.


Most Helpful Guy


Have an opinion?


Send It!

What Girls Said 2

  • It could be a million and one things. Probably needs a service before anything else.

    New tires: have you go the right pressures in them?

  • do you have a leak in the tank? the fuel hose? it only needs to be a small one to make difference... what about the fuel pump? When did you service it last? How many revs does it do per km? has that changed at all?

    • Could be many things but this was my first guess. I've experienced this.

What Guys Said 5

  • Maybe something has gone wrong with the cars EFI system or computer? Maybe it has a bad O2 sensor which I am not sure but I think that can make a car use more gas. Google that.

  • Are you tires balanced and filled o proper levels... is maf sensor performing properly

    • All filters changed... oil probably good but I mean air filter and fuel filter

    • Show All
    • Thanks brother. The fact that I am in FL could have an impact. But this is the same place climate where it was giving better all these years. In any case, I have to use all the tips here. Thnx again.

    • Np man, good luck

  • Air filter, cylinder isolation. You are losing power somewhere.

  • Could be a lot of things. Start with a complete tune up, try 02sensors and catalytic converter. Put some fuel system cleaner in it. If none of that helps, try found a vacuum test and a compression check

  • bad cat convertor, clogged PSV valve, bad rings if you are seeing smoke, spark plugs fouled, could be a lot of things.
    Change the PCV valve
    Change the oil
    Check the CATS
    Replace the Transmission Filter (tough job if you dont know how)
    Check the engine vacuum

    • Thank you sir. That is a lot of tips that I need to look into :) I appreciate it.

    • One easy fix, that I forgot to mention is to reset the car's computer. Sometimes they simply are using the wrong air/fuel mix. Also you should use an MAF cleaner on the MAF sensor. That affects the mix. (I meant to say PCV valve in the first line, not PSV)

    • Thanks again. As you can see my ignorance, I did not even catch that error. '(