Excessive fuel consumption.

[Luke]

Honda Jazz EX CVT 2012. Display shows 26.9 mpg whereas if i remember correctly, the car should be doing 40mpg officially and unofficially, 35mpg around town. Only had the car for about a month. Car has done 36k with full Honda service history. Car was serviced in March this year but i checked the air filter anyway and its looks like new. Also checked tyre pressures and coolant & oil level and mass air flow sensor. It has been bitterly cold but will be surprised if mpg falls this low due to this. I can't think of anything else except the brakes binding. I even put a half tank Shell V power but no real difference. Car is mainly used for local driving. Any suggestions please.

 

[Trevor]

Hi Luke....welcome to the Forum

 

I would imagine that a car of this age with this mileage has probably not gone out of town much.

I have had similar cars in the past that also have suffered from low MPG and performance and with longer runs out of town and gradually increasing the engine load and revs have managed to clear the engine out with much better results on performance and economy.

It helps to add a tin of Redex or similar to assist the clean-up but otherwise, it is a case of bedding the engine in after poodling around town for so long

 

Let us know how it all goes

[Luke]

So i have had the brakes checked and my trusted mot garage put the Jazz on their rolling road to check for brakes binding and tyre state. It all came back clear.

I have noticed if i take the car on the motorway, the mpg rises steadily and i can get up to 60 mpg. But goes back to a sorry 26- 28 mpg around town.

Looking at this from another angle, the display shows 260 miles when tank is full and i think there is something wrong right there as that is way too low. Anyway both trip meters are set to zero. I only get 192 miles before the low fuel warning light comes on. A full tank costs me £40 -£45 every fortnight.

My Golf Mk5 1.6 FSI  lasts a whole month on on £50 Shell V Power.

I am now thinking spark plugs and fuel filter both of which are a nightmare to change on this car. Other than that the car is very quiet and smooth. No misfire's etc but i notice the fan comes on and off a lot.

I am also looking to change the oil but still trying to find which one is most suitable. This is driving me bonkers.

 

[Trevor]

Changing the oil will definitely help as if washed down with fuel then the compressions will be lowered and less engine performance leading to higher fuel consumption.

Also, check that the air conditioning is not on by default as on a smaller engine this will lead to huge power draw from the engine

[Bradway7]

I had a lovely 2010 semi automatic Jazz, happily getting 45 mpg mostly tootling around town, with a couple of longish runs now and then.  Then I stupidly allowed the Honda dealership to persuade me to trade this in last July for a 2013 fully automatic Jazz.  I am now getting about 31.5mpg in spite of resetting the meter several times thinking it must have been a previous less than careful driver.  I have pumped the tyres up to the recommended levels, but it just seems to keep going down.  I am an elderly lady relying on those who know to advise me what else I can do to get this mpg up higher.  Am i expecting too much to think it should be at least 40mpg?  Your advice would be appreciated.  Thanks in advance,

[Annabel]

I have a 2021 Hybrid Jazz and I'm getting 65 mpg. Happy days

[Trevor]

On 12/8/2022 at 8:22 PM, Bradway7 said:

I had a lovely 2010 semi automatic Jazz, happily getting 45 mpg mostly tootling around town, with a couple of longish runs now and then.  Then I stupidly allowed the Honda dealership to persuade me to trade this in last July for a 2013 fully automatic Jazz.  I am now getting about 31.5mpg in spite of resetting the meter several times thinking it must have been a previous less than careful driver.  I have pumped the tyres up to the recommended levels, but it just seems to keep going down.  I am an elderly lady relying on those who know to advise me what else I can do to get this mpg up higher.  Am i expecting too much to think it should be at least 40mpg?  Your advice would be appreciated.  Thanks in advance,

 

I think with town driving that the MPG you are achieving is reasonable but would improve it taken on a long fast run every so often and in extra-urban environment it would increase even more

[Trevor]

On 12/13/2022 at 6:23 AM, Annabel said:

I have a 2021 Hybrid Jazz and I'm getting 65 mpg. Happy days

 

That's a great MPG and must be from using faster and quieter roads i imagine?