Winter fuel mileage...I have concerns !

[MustardTiger]

What's people getting for fuel economy in the cold/winter? Below is my average for a 6 hour drive. No head winds, no cargo, just me in the truck, and the only potentially effecting mod is 285/70r17 SL tires.

-Temperature -21c (about -6f)
-110km/h (~68mph) cruising speed, flat prairie
-15.8L/100km (~14.8 mpg US)...it actually landed at 16.1L/100 when I got home
-Maximum safe driving range...only 350km (~218 miles) !!
-Fuel used is 87, top tier

My old 2nd gen 5.7 Tundra got the same gas mileage in conditions like this, and that was a real truck with a real motor!!

I realize fuel economy drops in the winter...wasn't born yesterday. But like I said above...this is v8 half-ton territory...possibly worse

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[Kjc]

It has alot to do with the tires... My mileage is worse than last year when I had the stock tires... Now running 285 70 17 also and avg 14 mpg.... Temps have been between 0°-20°f....so I'm usually warming up the truck for at least 10 mins.... Mostly short trips 10-20mi at a time

 

[scythanith]

I am the same or worse, 15-20l/100 km in the winter. Still on factory rubber.

 

[Will721]

I was actually pointing out the issue in the main fuel economy thread. It's all down to the software, and more specifically, how the ecu is controlling the transmission to maintain temperatures. It seems even with shutters these trucks struggle to maintain temperatures in the cold. The ecu has very aggressive controls to try and maintain those temperatures too. The truck hangs at higher rpm in low gears until set points in coolant, engine oil temp, and trans temp are reached. Even when switched to "manual mode" you cannot force a shift into higher gears unless those temps are maintained. Torque converter lock up seems all but impossible to achieve below 20*F. Another observation is that at very low temperatures the trucks will actually start cooling back down as if the thermostats are bypassing too much coolant.

It's almost as if the cooling systems work too well, but funnily enough the trans still had a tendency to overheat in the summer months. What I'd really like to know is how the guys with aftermarket trans coolers are doing in the winter months. A direct comparison to a stock truck would be nice.

 

[MT-Taco]

My gen 2 tundra 5.7 was about 10-12 mpg in below 0F temps, LT305/70r17’s My Tacoma is 15-17 below 0F mpg, SL285/70r17’s.

 

[MustardTiger]

@Will721 good points. And given that the T24A in hybrid variant achieves up to 41% thermal efficiency...engine cooling efficiency is quite a balancing act, especially in extreme cold operating conditions from what I can see. In addition to that, with burning extra fuel in cold operating conditions, combined with low tension piston rings...this is a recipe for oil dilution, which I'm experiencing. After my 6 hour drive today, my dipstick is now 1/2 inch above the full mark!! I'm estimating that additional 1/2 inch is about 300ml...which equates to 5% dilution. So with 0w20 oil..and that amount of gas in the oil, it shears way below the 20 weight viscosity grade.

 

[izzy]

had a tendency to overheat in the summer

It runs hot but shouldn't overheat with stock cooling. I did worst case scenario basically, sub 10mph crawling for 10 miles in 90F weather and in 4L the trans didn't overheat.

Gotta use the gears.

I have noticed though, if you're doing city driving then transition to freeway driving, the transmission will actually cool down, if it's cold enough out. From 180F to 160F. I imagine the shutters are closed at that point, but the cooling system is still very effective.

Imo the transmission shifts best between 180F and 200F. Any colder and it's definitely more jerky.

As for OP I'm sure wider than OE tires + probably below 30psi due to external temp is also definitely not helping your MPG situation.

 

[oxi]

Nobody buys a body on frame vehicle and worries about mpg's.

It goes down in the winter due to reformulated fuels, colder tires that need warming up, dense cold air, running fans to keep windshields clear.

My 2025 Camry SE hovers around 40 mpg in winter and 45 to 48 mpg in summer. Running larger Blizzak's on 16's from my stock 18's does not help, but running the fan hurts. If I just use the heated seat option and keep the fan off, my mpg's climb on the Camry. Runing fans with smaller engines will lower your mpg's.

 

[Crazy Mary’s Husband]

Nobody buys a body on frame vehicle and worries about mpg's.

It goes down in the winter due to reformulated fuels, colder tires that need warming up, dense cold air, running fans to keep windshields clear.

My 2025 Camry SE hovers around 40 mpg in winter and 45 to 48 mpg in summer. Running larger Blizzak's on 16's from my stock 18's does not help, but running the fan hurts. If I just use the heated seat option and keep the fan off, my mpg's climb on the Camry. Runing fans with smaller engines will lower your mpg's.

How do electric fans figure into it?

 

[Will721]

How do electric fans figure into it?

Laws of thermodynamics. Technically if you are running the heat in your truck, the engine is releasing that much more heat. The goal of course is to maintain temperature so more energy is requires to replace that heat, meaning more fuel burn. Plus running of any electronics such as the blower motor increases the load on the alternator, which is powered by the engine and therefore results in more fuel burn. Of course how much of a difference would it make? No idea, I'm not that good at math nor an engineer. But then again using the same argument, the heated seats burn more fuel too.

I would also argue that yes, people buying body on frame vehicles can be concerned by fuel economy. If they weren't, there would be no need for variation and everyone would own full size trucks. The whole point of a midsized truck is better fuel economy especially when the price gap between the two is shrinking.


Reguardless, whether gas or hybrid my observation of the difference transmission control is far more abnormal. I've owned many vehicles in the past, although none quite this new, but the difference in economy in different temperatures is vastly different in these trucks vs other vehicles. Sub zero temperatures are cutting the mpg nearly in half is not the same as the few mpgs I've experienced. My Dakota, diesel Ram, and e46 all experience around a 3-4mpg drop in well below zero temperatures on the same drive. My Tacoma on the other hand has dropped 7-8mpg and I haven't even driven below zero yet. I'm really curious what it will do once it drops another 10-15 degrees below zero.

 

[coldtaco]

I'm averaging around 15mpg in town too, stock tire size, hybrid TRD OR

 

[crepr12]

21+ around town...stock

 

[Crazy Mary’s Husband]

Laws of thermodynamics. Technically if you are running the heat in your truck, the engine is releasing that much more heat. The goal of course is to maintain temperature so more energy is requires to replace that heat, meaning more fuel burn. Plus running of any electronics such as the blower motor increases the load on the alternator, which is powered by the engine and therefore results in more fuel burn. Of course how much of a difference would it make? No idea, I'm not that good at math nor an engineer. But then again using the same argument, the heated seats burn more fuel too.

I would also argue that yes, people buying body on frame vehicles can be concerned by fuel economy. If they weren't, there would be no need for variation and everyone would own full size trucks. The whole point of a midsized truck is better fuel economy especially when the price gap between the two is shrinking.


Reguardless, whether gas or hybrid my observation of the difference transmission control is far more abnormal. I've owned many vehicles in the past, although none quite this new, but the difference in economy in different temperatures is vastly different in these trucks vs other vehicles. Sub zero temperatures are cutting the mpg nearly in half is not the same as the few mpgs I've experienced. My Dakota, diesel Ram, and e46 all experience around a 3-4mpg drop in well below zero temperatures on the same drive. My Tacoma on the other hand has dropped 7-8mpg and I haven't even driven below zero yet. I'm really curious what it will do once it drops another 10-15 degrees below zero.

Lately I’ve been playing with this ChatGpt boogeyman and love it or hate it, here is what it gas to say:

“Why do I get lower mpg in winter?”


Lower MPG in winter is very common, and it’s a mix of physics, fuel chemistry, and how vehicles operate in cold weather. For your Tacoma (especially turbocharged), these factors stack up.


1. Winter gasoline has less energy

Refineries switch to winter-blend fuel to improve cold starting and reduce emissions.

• Contains more volatile components (like butane)
• Lower energy content per gallon
• Typically causes 1–3 MPG drop by itself

Nothing is “wrong” with the truck — the fuel just doesn’t go as far.














2. Cold engines run richer longer








When it’s cold:

• The engine stays in open-loop longer
• Extra fuel is injected to stabilize combustion
• Turbo engines enrich even more to protect components

Short trips hit MPG hardest because the engine never fully warms up.














3. Increased mechanical drag








Cold temps affect:

• Engine oil (thicker until warm)
• Transmission fluid
• Differential and transfer case fluids

Until everything warms up, more energy is wasted overcoming friction.














4. Higher aerodynamic drag








Cold air is denser:

• More resistance at highway speeds
• MPG loss becomes noticeable above ~45 mph

This is pure physics and unavoidable.














5. Tire pressure drops








For every 10°F drop, tire pressure falls about 1 PSI.

• Underinflated tires increase rolling resistance
• Many people lose 3–6 PSI by mid-winter without realizing it

This is one of the easiest fixes.














6. More idling & warm-ups








Winter habits matter:

• Remote starts
• Letting the truck idle to warm up
• Clearing snow while running

Idling = 0 MPG, and modern engines don’t need long warm-ups.














7. Electrical loads increase








Winter uses more power:

• Heated seats
• Defrosters
• Heated mirrors
• Blower motor

The alternator load increases, which slightly increases fuel consumption.














What’s


normal


MPG loss?








For most trucks:

• 5–10% drop is typical
• 10–15% isn’t unusual in cold climates with short trips

For a turbo Tacoma doing mixed driving, that’s very normal.














How to minimize winter MPG loss

• Check and adjust tire pressure monthly
• Drive off gently after 30–60 seconds (no long idling)
• Combine short trips when possible
• Use the recommended oil weight (0W-20 / 0W-30 if specified)
• Keep snow and ice off the truck (weight + drag)

If you want, tell me:

• Your current MPG
• Average trip length
• Typical winter temps

I can tell you whether what you’re seeing is perfectly normal or worth investigating.

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