Yaris 2019 Icon Tech fuel range has decreased

[sufy]

Hi

My Yaris 2019 Icon Tech was 350 miles on a full tank and low I'm only getting around 300 miles. Why is that?

Thanks

[Jasper.]

I would like to guess that it's purely down to the cold weather  ??

[Parts-King]

Lower winter temperatures, engine runs more, common with Hybrids for the MPG to reduce a lot in winter 

[Mojo1010]

These questions gets asked many a times, do a search on here or the web. Range is an estimate, cold, short journeys etc. 

[Cyker]

Ironically mine's been going up   I'm on track for 72mpg on this tank  

It has been super warm here tho' - The temperature shifts are crazy; Was -3 last week, now +12!!

 

[Stevie J]

Cold weather, plain and simple. The engine uses a lot more fuel on cold start when the weather is round freezing point than it would in warmer weather. If I start my car up on really cold evenings after coming out of work and leave the drivers door open longer than 30 or so seconds, i get knocked out by the smell of petrol coming out of the exhaust - they really do put some serious enrichment to the mixture on the 1.33 petrol engine - it is the same really as when older cars with manual chokes used to have to be started in cold weather with the choke knob pulled fully out. 

Driving in winter also used the headlights, heated rear window, blower motor and other accessories more, which puts more load on the alternator and means more fuel is used. The heater in the car uses hot water from the coolant, which reduces engine temp and means more fuel gets used

All in all, my own miles per gallon is reduced to just 30mpg round town and 47mpg on a longer run in colder weather. Local short journeys round town in winter at night will seriously reduce fuel economy.

[Cyker]

Yeah the auto-chokes on modern cars seem quite aggressive! I reckon if I could feed my Mk4's exhaust back into the intake I'd get another 10HP there's so much petrol fumes in it  

But the main sources of efficiency loss in winter is just the engine is cold - heat engines are really inefficient when they're cold - and tyre pressures being too low; That significantly increases rolling resistance which saps kinetic energy.

Someone told me the air is also denser when cold, which means the car adds more fuel to maintain the A/F ratio, and also creates more air resistance, esp. at speed, but I can't imagine these are as significant.

 

 

[Stevie J]

Indeed, cold engines are inefficient because there is more drag on the moving parts with cold oil being thicker and harder for the engine to overcome the resistance until the oil warms up. Using a lighter, thinner oil such as 5W30 is better than higher viscosity 10W40 or 15W40 at lower temps. The higher the viscosity, the more resistance the oil causes to the engine turning when it is cold as some oils can become like treacle when the temp drops below freezing. The best thing to do is always change the engine oil every 6000 miles and use lower viscosity oil like 5W30. Modern cars dont need thick oil unless there is a reason for needing it like a severely worn engine that would burn too much thinner oil.

Tyres should, as you say, be kept at the recommended pressures all year round, but in winter the cold weather will tend to reduce the pressures for some reason, which is why the TPMS light can come on at the first sign of cold mornings and then go out when the day warms up.

Colder air is denser than hot air, yes, thats why hot air rises, it is less dense, and the cold air above it will fall down to take its place. I think thats the purpose of the air temp sensor in the air intake system, used in conjunction with the Mass Airflow Sensor, it is used by the ECU to all more fuel to the engine if the intake air temp is colder.

[Bernard Foy]

17 minutes ago, Stevie J said:

Indeed, cold engines are inefficient because there is more drag on the moving parts with cold oil being thicker and harder for the engine to overcome the resistance until the oil warms up. Using a lighter, thinner oil such as 5W30 is better than higher viscosity 10W40 or 15W40 at lower temps. The higher the viscosity, the more resistance the oil causes to the engine turning when it is cold as some oils can become like treacle when the temp drops below freezing. The best thing to do is always change the engine oil every 6000 miles and use lower viscosity oil like 5W30. Modern cars dont need thick oil unless there is a reason for needing it like a severely worn engine that would burn too much thinner oil.

Tyres should, as you say, be kept at the recommended pressures all year round, but in winter the cold weather will tend to reduce the pressures for some reason, which is why the TPMS light can come on at the first sign of cold mornings and then go out when the day warms up.

Colder air is denser than hot air, yes, thats why hot air rises, it is less dense, and the cold air above it will fall down to take its place. I think thats the purpose of the air temp sensor in the air intake system, used in conjunction with the Mass Airflow Sensor, it is used by the ECU to all more fuel to the engine if the intake air temp is colder.

And that’s why a golf ball travels further in the summer than on a cold winter day 👹🏌️‍♂️

[bathtub tom]

2 hours ago, Stevie J said:

 If I start my car up on really cold evenings after coming out of work and leave the drivers door open longer than 30 or so seconds, i get knocked out by the smell of petrol coming out of the exhaust

That's why you should drive off straight away -quicker warm up.

I used to leave my girl friends house adjacent to the M1, It used to pain me to use so much throttle on the slip road, so I used as little as possible until it warmed up, then I gave it some beans!

[wildtapholer]

23 hours ago, Bernard Foy said:

And that’s why a golf ball travels further in the summer than on a cold winter day 👹🏌️‍♂️

It does depend on how hard the ground is as well, T off with a ball out of your warm pocket.😁