Interesting. I didn't realize this.
How much mpg do you lose in winter?
- Thread starter BillyHW
- Start date
Interesting. I didn't realize this.
My wife’s Tiguan only loses about 1 MPG and normally gets 30MPG. I believe it’s less because she drives 35 miles each way highway to work so majority of miles are with warmed up engine. Not short trips with cold less efficient motor .
Yep, good reason not to own a dodge, everything for the truck is cheap but the gas isn’t even with it moving under 1500 miles a year.
I've estimated this based on data logging fuel consumption on a couple of different vehicles. Generally speaking, the electricity cost will be about the same as the fuel savings, if the block heater is used for 2-3 hours before driving. Shorter plug-in times are more efficient and economical than longer ones, and there's a greater benefit to fuel economy in colder weather.
About 15% less for my QX60. I run 4 snows on minus 1" rims, with TPMS mounted and maintain at least 33psi all around. Premium Costco gas as well.
My ram drops from 16-17mpg to 14-15.
It doesn't seem to be the case with our '07 Dodge Grand Caravan - I've used the ScanGauge to monitor the instantaneous fuel consumption at idle. It doesn't change when the selector is moved from any of the other settings to defrost. (If it did, I'd pull the AC fuse for the winter.)
Just the fuel savings from using a block heater are huge.
Some years ago I did a comparison, doing the same run when the engine started off cold (coolant temperature -20°C) vs. warmed by a block heater (c. +20°C). As I recall, the cold-start short trip (c. 8 km) yielded about 5 km/l (awkward format, but that's how the early ScanGauge presented gas mileage) and the pre-warmed trip was 8 km/l.
5 km/l works out to 20 l/100 km, whereas 8 km/l is 12.5 l/100 km.
To run the block heater 3 hours/trip for 12.5 short trips would result in 37.5 hours of block-heater usage (for 100 km of short trips). The block heater was 400 W, so at present prices would cost $0.04/hour to run.
Four cents per hour x 37.5 hours = $1.50.
Let's use the present cost of gasoline - $1.50/litre.
Without using the block heater, I'd use 20 l of gas = $30.
With the block heater I'd use 12.5 l = $18.75.
So over 100 km of short trips, block heater use would cost $1.50 in electricity but would save $11.25 in gasoline.
This is aside from reduced wear and tear on the engine, less fuel dilution of the oil, faster cabin heat, reduced wear on the starter, battery, and charging system ...
But do I use the block heater myself? Not often, because I park in an attached garage which doesn't get terribly cold, and there are too many horror stories of garage fires caused by block heaters.
Outside in cold weather, yes!
This is great, thank you.
My accent usually averages 40mpg in mixed driving all summer. Winter time I'm looking more at 35mpg. could be as low as 33mpg if it's realllllly cold. The car just never gets a chance to warm up with all my short trip stoplight driving.
Yes, the engine would operate at lower throttle when the air is colder. This reduces engine efficiency since it increases pumping losses. The engine has to work harder to pump air through the throttle restriction.
The engine may have more advanced ignition timing when the intake air is cooler though, which would increase efficiency. At high throttle, the engine may be more efficient when the air is cooler.
Up to 12% depending how many longer trips we take (less time warming up/running open loop).
Typical summertime is around 24 MPG and typical wintertime is 21-22 MPG.
Typical summertime is around 24 MPG and typical wintertime is 21-22 MPG.
Thanks! I should have added that the advantage that a block heater provides is greater for short trips.
I used the example of 8 km because that's what I had data for.
For shorter trips than that, the difference would have been more extreme.
For longer trips, the advantage conferred by starting with partly warmed coolant is much less.
I used 3 hours as typical, because the heating effect of a block heater levels out quickly. Something like 50% of the temperature gain is achieved after an hour, 90% after 3 hours, and there's no further gain after 4 hours.
The coolant temperature in my vehicles has consistently maxed out at around 23°C after about 3 hours on a block heater, with ambient temperature varying from -15 to -40°C.
One more advantage was that our '97 Mazda MPV used to idle high until warmed up. I didn't like torturing the u-joints by putting it in D at greater than 1500 RPM. It dropped to 1500 when the coolant temperature hit about 31°C, so using the block heater really shortened the warm-up. (No problem with our other Mazdas, which also idled high when cold, but had manual transmissions.)
Hermann
Site Donor 2023
Last winter the Maverick Hybrid went from 41-42 mpg in the spring, summer and fall. dropped to about 38 in the Dec thru March period.
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