Winter fuel consumption?

[Mr_Groundhog]

Does your car drink more in the winter, with colder temperatures out there?

In the last few weeks, I have the feeling (just a hunch) the car's self-reported fuel consumption (I know it isn't accurate but it is constant, so I'm using it as a reference) has increased a bit. From being between 50 to 47 mpg with low effort, now I'm finding myself driving economically on purpose just to see if I can still achieve those figures. 

I have seen similar topics but about models in particular, and I guess each model can be different so I thought I would ask here specifically to you IS300h people. Apologies if this is a duplicate. 

[wharfhouse]

6 minutes ago, Mr_Groundhog said:

Does your car drink more in the winter, with colder temperatures out there?

In the last few weeks, I have the feeling (just a hunch) the car's self-reported fuel consumption (I know it isn't accurate but it is constant, so I'm using it as a reference) has increased a bit. From being between 50 to 47 mpg with low effort, now I'm finding myself driving economically on purpose just to see if I can still achieve those figures. 

I have seen similar topics but about models in particular, and I guess each model can be different so I thought I would ask here specifically to you IS300h people. Apologies if this is a duplicate. 

Yes, cold weather hits the fuel consumption on short runs/ low speed journeys quite hard as the ICE has to run longer to get up to heat and run more to keep the cabin warm. If I understand it correctly, the traction Battery will also not deliver so much power when cold, I believe it's warmed from the cabin air so until the cabin is warmed up and the Battery has warmed up it won't deliver so much power as warm days so the ICE has to do more until ambient temperature is reached. On runs of a few tens of miles in cold weather economy will fall some 10-20% over warm weather. On long motorway /  A road runs (a few hundred miles) then it's much less noticeable as once everything is warmed up it stays there with the ICE running all the time the cabin stays warm (waste heat from the engine at this point) and the traction Battery is warmed up properly  (and so can deliver as per warm weather) and so the first few miles of low mpg are amortised over the remaining hundreds of miles.

[IS300FSPORT]

Since refuel reset the MPG 2 weeks ago after a full tank of fuel from Coscto using the premium fuel.

Average was 17MPG now at 19MPG its slowly trying to go up.

Thr average usually sits around 33MPG & on motorway seen it upto 50mpg. 

This is strictly local mileage on eco mode using heaters & heated seats & the rear demister. Less than 2 mile a day journey doing the school pickup sat idle for at least 15 mins, iv done approx 60 miles not exactly great MPG for a Hybrid.

The Battery health check & tyre pressures are good too.

Maybe its my right foot 

[wharfhouse]

6 minutes ago, IS300FSPORT said:

Since refuel reset the MPG 2 weeks ago after a full tank of fuel from Coscto using the premium fuel.

Average was 17MPG now at 19MPG its slowly trying to go up.

Thr average usually sits around 33MPG & on motorway seen it upto 50mpg. 

This is strictly local mileage on eco mode using heaters & heated seats & the rear demister. Less than 2 mile a day journey doing the school pickup sat idle for at least 15 mins, iv done approx 60 miles not exactly great MPG for a Hybrid.

The battery health check & tyre pressures are good too.

Maybe its my right foot 

Yes, the very low mpg is no surprise if you are only doing a few miles with all the electrics on as the car will be using ICE all of that time, especially in cold weather. I use Costco E5 all the time as it gives a decent uplift in mpg over E10 for just a few pence more per litre more and easily pays for itself in better fuel economy. My mpg on a decent run (according to the car computer) is generally between 48mpg and 52mpg (at least for journeys that are over about 20 miles - I have seen 60+ mpg from time to time on A roads doing around 40/50mph in ambient temperatures). On the motorway I am generally one of the faster cars as I'm often traveling on business or long journeys and so have places to be and so don't dawdle but still see 48mpg+ regularly.

[Mr_Groundhog]

This is great to hear guys, thanks a lot for the insights.
A bit of a relief that I can rule out any malfunction in the car...

[Notamech]

Yes i do ~5 miles each time i use my car so primarily short trips and in the winter my fuel consumption is quite high. I guess the engine needs to stay on longer to warm up due to lower temperatures plus theres demand on the system from the heated seats window defoggers ac and so on. The trip computer stated consumption ranges between ~27-30. In the summer i can live without using the ac most days and for similar distances i get a much higher 45-50

[_3rd]

IS200t: during the winter slightly better MPG (18” wheels): 20.2.

Summer MPG is about 19.5 (19” wider alloys)

[GMB]

Is200t the biggest factor is the type of trip such as around town or country. For me no difference summer or winter but town can be as low as 21mpg 12-32 mph average and country/motorway 68-73mph average usually 28mpg. Using tesco momentum and a light right foot especially after cold starts.

[DBIZO]

On 11/23/2023 at 2:22 PM, Mr_Groundhog said:

Does your car drink more in the winter, with colder temperatures out there?

In the last few weeks, I have the feeling (just a hunch) the car's self-reported fuel consumption (I know it isn't accurate but it is constant, so I'm using it as a reference) has increased a bit. From being between 50 to 47 mpg with low effort, now I'm finding myself driving economically on purpose just to see if I can still achieve those figures. 

I have seen similar topics but about models in particular, and I guess each model can be different so I thought I would ask here specifically to you IS300h people. Apologies if this is a duplicate. 

Just seconding those before me with some additions. Yes, winter consumption can be fairly higher for a combination of factors. Engine starts cold, takes time to warm up to reach optimal operating temperature. But  in a hybrid, also the traction Battery takes much longer to warm up which something you really need for fuel economy.

The NiMH Battery cells need to warm up to 25C or more, ideally, to give you their full benefit of regen and discharge performance. Based on reverse engineering I've seen, there is no active thermal management on the Battery pack other than a cooling fan if it gets too hot. The power delivery profile of these hybrids change noticeably once the system is all warmed up, foremost in your low-end electric torque and also the time the engine can spend off in EV mode. With a cold Battery, the car feels anaemic which will probably make you apply more throttle, which will be coming from the engine.

The other thing other may have not mentioned is air density is greater in winter. This matters if you do 50+ as it increases the drag component of the overall resistance pushing against the car. Some say a naturally breathing engine gets more economical with cold air, but from experience the extra drag outweighs that gain it seems. 

[Mr_Groundhog]

Oh wow, all of these are very insightful points, thank you 🙂