sudden heavy fuel use?

Norman_Castle

Did the mpg change when the new tyres were fitted? Are they the same profile/size?

ris2015

Petrol is blended differently in winter, it has a higher RVP to allow it to evaporate at lower temperatures. This results in lower mpg
How much ethanol is in your petrol? moving from E5 to E10 can see a 3-4 % drop in mpg.

DUTR

Jackmydad said:

DUTR said:

sophlouwhit said:

maybe i am over thinking things but i have noticed a fairly drastic drop in MPG. we have a toyota yaris, 2013.

does age effect MPG? does winter effect MPG?

spark plugs are original, car done 80k

new tyres and always kept to good pressure

yearly full service

I would say overal a well maintained car

I have noticed this sudden dip in MPG, where it seems to be drinking a LOT! we used to get 45mpg average now 38mpg average (this is using milage and liters put in vs car computer which i do not trust). Not sure what to think.. does MPG decrease with age? what can we do to help it? to add we add a fuel cleaner which claims to clean injectors every 6 months, once winter and once before MOT (we never used to do this and its a new thing as of last year and hasnt especially helped MPG -2019 average compared to 2018-

Winter certainly has a negative effect on fuel consumption for the reasons and more stated in the replies, I notice a 4mpg difference (on the computer) compared with the warmer seasons, however I don't notice any difference in fuel spend for the week. 

That's because when it's cold, the world shrinks, and so the miles are shorter. . .

Lol, in my case my MPG on average is in the low 30s around town in the winter mid 30s in the summer , on a run it will jump up to 40+mpg, I don't run the tank from full and top it up as I'm carting around the weight of fuel which I'm not using.