Winter Fuel Consumption

[Cypry 1]

I wonder if anybody can let me know if the fuel consumption on my Series 3 RX450H is about 2 to 3 mpg worse in this cold weather.

Is this a general trait at this time of year ?

[08ISF]

My series 4 RX fuel consumption gets worse by varying amounts in cold weather. I think it is a combination of  Battery performance degraded due to low temperature, and the engine having to run more to keep the cabin warm. Much worse if the vehicle is only used for short runs as the petrol motor is running for a greater portion of the time. Down to 25-30 mpg over the last week!

[Pielight]

With all of my cars I've owned over the years, I've observed a noticeable drop in fuel economy. An engine isn't at its best until thoroughly warmed up which can take considerable time in cold weather - the temp gauge isn't a complete indication of engine temperature.

My GSF also has an oil temperature gauge and this takes much longer to reach operating temperature than the coolant gauge. 

[Illogan]

Jim - - the answer is yes....... your fuel consumptoin will worsen.

The external air is colder ( it takes more fuel to warm up your engine to the optimum operating temperature, and you'll use fuel to warm the inside of your cabin, and the fans to push the warm air around)

More of the day is darker (aka 'night') - so the car uses more fuel creating electricity for your lights

 

My fuel consumption deteriorates by between 1 and 1.5mpg

[Spottedlaurel]

2 hours ago, Cypry 1 said:

I wonder if anybody can let me know if the fuel consumption on my Series 3 RX450H is about 2 to 3 mpg worse in this cold weather.

Is this a general trait at this time of year ?

Yup. I'm probably getting a bigger drop than that, but at present I'm rarely doing any journeys longer than 10 miles.

[Herbie]

3 hours ago, Pielight said:

An engine isn't at its best until thoroughly warmed up which can take considerable time in cold weather - the temp gauge isn't a complete indication of engine temperature.

My GSF also has an oil temperature gauge and this takes much longer to reach operating temperature than the coolant gauge. 

With no actual numbers on the gauges these days, how do we know what the proper operating temperature should be?

[Prince Bob]

11 hours ago, Cypry 1 said:

I wonder if anybody can let me know if the fuel consumption on my Series 3 RX450H is about 2 to 3 mpg worse in this cold weather.

Is this a general trait at this time of year ?

I wish my winter consumption was only 2 to 3 mpg worse! I'm seeing a drop of about 20% on short journeys, but it's to expected, batteries don't like cold weather and the car uses the engine alot more, a 3.5 V6 has to get energy from somewhere. Just grateful I don't have a full EV. 

[JBPRX400h]

Absolutely normal to see worse fuel consumption in colder weather as per the comments above.

Also wind direction can have a huge effect. We regularly drive 400 miles down through France and back and the route we take is almost due north/south. If the prevailing wind is behind us we easily get 40MPG but if it is a head wind this can drop to the low 30's.

Driving on wet roads also increases fuel consumption which makes sense if you think about how much energy you would use if you had to sweep all that water out of the way in front of the tyres!

JBP

[Cypry 1]

Thanks very much for all your info and feedback

[ColinBarber]

22 hours ago, Herbie said:

With no actual numbers on the gauges these days, how do we know what the proper operating temperature should be?

When it's in the middle 🙂 

[Gliderpilot]

Last weekend I did a 200 mile trip south on the M6 M5 and on to Swindon, I filled up before going and averaged 36.4 for the trip. I did the same for the way back 2 days later, same roads etc and got 33.5. It varies from day to day, but I always knew that the UK sloped down to the south he he.

[Illogan]

32 minutes ago, Gliderpilot said:

Last weekend I did a 200 mile trip south on the M6 M5 and on to Swindon, I filled up before going and averaged 36.4 for the trip. I did the same for the way back 2 days later, same roads etc and got 33.5. It varies from day to day, but I always knew that the UK sloped down to the south he he.

The reason's obvious Peter - - - It's a punishment for 'going down South'

[Pielight]

On 1/20/2022 at 12:00 AM, Herbie said:

With no actual numbers on the gauges these days, how do we know what the proper operating temperature should be?

As Colin alluded to  the actual numerical value is not so important...the normal segment of the gauge (eg. halfway) will suffice to show that the coolant has reached optimal operating pressure. 

[Herbie]

On 1/20/2022 at 10:40 PM, ColinBarber said:

When it's in the middle 🙂 

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7 hours ago, Pielight said:

As Colin alluded to  the actual numerical value is not so important...the normal segment of the gauge (eg. halfway) will suffice to show that the coolant has reached optimal operating pressure. 

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Thanks guys but I'm afraid I already knew that 

My question is more curiosity rather than an absolute need to know, but it came after seeing a post in one of the Grom Vline 2 groups on Facebook where someone has installed 'Torque Pro' or something like that on his Vline. It shows some fancy schmancy dials and gauges that display numerical values and I was wondering just how accurate these displayed values are:

[ColinBarber]

5 hours ago, Herbie said:

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Thanks guys but I'm afraid I already knew that 

My question is more curiosity rather than an absolute need to know, but it came after seeing a post in one of the Grom Vline 2 groups on Facebook where someone has installed 'Torque Pro' or something like that on his Vline. It shows some fancy schmancy dials and gauges that display numerical values and I was wondering just how accurate these displayed values are

The values should be accurate as they would have been read from the engine ECU with reasonably calibrated sensors using the OBD port. What I'd question is the validity of the RAG (or RAYG) segments that someone has used - are they correct for the specific vehicle or just generic approximations of what is considered correct.

[Gene]

I used to get 28 mpg on my RX400H - which dropped to 22, just back from 100,000 mile service and over the last 40 miles it is down to 16mpg - thank heavens it is a hybrid;-

[ColinBarber]

10 minutes ago, Gene said:

I used to get 28 mpg on my RX400H - which dropped to 22, just back from 100,000 mile service and over the last 40 miles it is down to 16mpg - thank heavens it is a hybrid;-

If your current mpg figure includes the time at the service then that is somewhat expected as they leave vehicles idling for excessively long periods of time in the workshop.

Also when you have a service, or the Battery is disconnected, it is always worth making sure the engine is cutting out and the vehicle switching to EV mode as you would expect - the 400h hybrid system can fail to initialise correctly and stop this occurring which impacts mpg. Get the engine up to temperature, turn off the heating system and make sure the engine cuts out when you are stationary.

I don't think I ever dropped below 23 mpg in my 400h, even in winter.