Why am I losing MPG?

I have a new Honda Insight. Great gas mileage at first. I have about 4000 miles on it and maintenance minder suggests I am about halfway to my first servicing. I've noticed that my mpg has gone down. I was getting 50-54 mpg at first. Now, I'm getting about 40-44 mpg same driving habits. Should I go for service now? What could it be? 

9 Answers

  • whoo
    Lv 5
    8 months ago

    Give it a good tune up .... if that don't fix the problem the carb. need a good cleaning . 

  • 8 months ago

    And it's not a hybrid engine? My guess is winter fuel, this is far less efficient. Colder engines are consumers. Air runs out of tires, trough the vents possibly or shrinking because of low temperatures and tires get worn out. The alternator in cars is elektro-magnet activated, what means you have variable resistance there and would use extra fuel for air conditioning (window drying, blowing) and riding with the lights on. Now think of the lead-acid battery that may last only 5 years and requires more charging, especially in winter. Older oil can be a ***** and engine tolerance is less then new, there is coal being introduced inside the engine also. Injection engines have air volume meters that make the board computer inject more fuel when the temperature of these two electrical wires do not reach their target. Same with high and low air pressure: in the mountains or in bad weather the air volume meter makes up with signaling for more fuel. The dealer takes a look at butterfly valves and idle and should look for contamination on these air volume meter wires in the throttle body also. Injected engines require cleaner for the injectors or are to be checked because small changes in injection make a big difference in fuel economy. 

  • Anton
    Lv 6
    8 months ago

    DUH!  You are not driving the same.

    You have comfortable with your Honda and and are having more fun.  

    More fun means burning more fuel. 

  • 8 months ago

    Replace the air cleaner.

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  • Scott
    Lv 7
    8 months ago

    You realize that nobody guaranteed your fuel economy would be "x". Are you familiar with the term "your mileage may differ"? It's doubtful there is anything mechanical that is wrong with your vehicle, which you said was new. If you are using the car's computer for your mileage calculations, they are not that accurate. The best way to determine your fuel economy is dividing miles driven by fuel used on a tank by tank basis.

  • 8 months ago

    I have a Prius which gets from 38 to 61 mpg depending on speed and temperature. The mileage is lower on cold mornings because cold oil is more viscous and causes more drag inside the engine. The mileage goes up a bit as the engine warms up. Cold tires don't flex as easily and have higher rolling resistance, which also reduces the mileage. If the day warms up the tires warm up and the mileage goes way up. Also, tires have lower pressure on cold mornings due to PV=nRT. Flatter tires also have higher rolling resistance. 

  • 8 months ago

    how are you determining that the mpg went down?

    Are you monitoring how much gas you put in the car and how far you are going?

    Are you reading the "car" stats?  The car stats have gone down because you have "more" information. 

    - the less data you have the more the car is swayed by external events.   If you sit in traffic for an hour when you only have 500 miles on your car, that is going to be have a much greater impact, than if you sit in traffic if you have 4000 miles and vice versa.  So the car is simply learning about what you are driving. 

  • Anonymous
    8 months ago

    And here you are with a brand new car, asking a bunch of strangers on a motorcycling forum why your mpg is poor. What you should be doing is asking your dealer.

  • 8 months ago

    Driving habits.

    Quick off the stop, Stomping the brakes when arriving at stops. Always in a hurry. 

    You drove comfortably, and easy when it was new and you were getting used to it. Now, you have experience and are more aggressive in traffic.

    Revving at stops, to hear the engine scream, and impress other drivers?

    When starting, gradually increase throttle, you are not in a drag race.

    When traffic permits, let the bike's throttle off and coast to the stop.

    Mind the traffic flow, you don't have to keep up with the fasted vehicles. You don't need to pass just because the occasional vehicle is only driving the speed limit.

    E: If it is not driving habits, then either you are using Cheap Fuel, or the computer adjustment is off. Presuming, You did not change Tyres?

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