Sudden loss of mpg

22 tundra westcott lift and 295-65/20 tires. October went from DE to PA and avg mpg was 20 hwy, City 14 with lift and tires.
Same exact trip to PA and got 14 hwy in late November.
Third trip to PA exact same roads and got 14 hwy again. What am I missing. Why 20 one time 14 now. Still getting 14 city also.

 

if you have changed nothing in between your MPG measurements, my thought that it would be the difference in the blends of gasoline that you put in your truck, while you may use the same grade of fuel each time (87-89-93), i live in ohio, so therefore i know that starting around the time frame that you state (Oct - Nov) the blends of gasoline at the pumps are being changed out, they are going from summer blend gasoline to winter blend gasoline, and winter blend gasoline has always gotten lower MPG as the winter gas doesn't need all the extras in it due to lower outside temperatures, your engine isn't being "cooked" in the engine bay in the winter, therefore the fuel doesn't need the extras in it to decrease knock and early detonation

but thats just my opinion, hope it helps

 

This has been stated as an early warning sign of bearing failure.

 

Here we go again, I got a flat yesterday, my bearings must be going.

Seriously though, this could be because of many things, my question for the OP would be how do you know what the mpg was between city and highway? Did you just take note of what it was before getting off the highway? Also, possibly you never reset the trip/mpg meter before the first trip? I know you list the lift and tired but were those installed after the 20 mpg?

 

So far I've read about 4 main things that kill MPGs on the new ones. First one is driving style, no one can help you there but you. Second would be the lift / level and 10 ply 35" tires everyone must put on their trucks upon delivery. Third is actually the bearing issue, and fourth is O2 sensors going bad or being bad. Several members have already had these issues.

 

I don’t even have a lift just 34” c load tires and I get like 16.5 mpg on road trips. City I’m usually around 14-15 mpg. Before I had new tires and wheels the best I could do was around 19 mpg.

20 mpg with a lift and 35s seems to be the questionable number here. 14 mpg sounds about right. But always manually calculate it to confirm actual fuel economy.

 

Colder weather and winter fuel will decrease fuel economy.

I'm in sunny California with winter highs in the 70s and my fuel mileage still drops around 1.5mpg throughout the "winter".

 

Cold and side or head wind will kill MPG

Plus just incremental times hitting the turbos increase fuel.

 

Other than Ryan, others have reported a drop?

 

reset the trip for all the trips. still don't get the sudden drop.

 

My clock is out......must be the main bearing

 

Hey pal...you want a taste of "winter"...pop up to my house in Canada

 

Yeh I see two environmental things change my best milage, the super summer heat and the deep cold, spring and fall I get my best MPG. I average around 18.5 with 34’s, long road trips doing 70 mph ish and I can get 19 ish. Back and forth to work 55 mph varies by season 17-20.

 

Why is this so shocking? ONE of the many reasons for drastically reduced mileage out of the blue is a bearing about to go. Plus, he's driving a 2022, which is probably the MOST prone. Maybe Occam's Razor applies here, maybe the OP just has a low tire that eats up an extra SIX mpgs???

 

I would think there would be a lot of noise coming from the motor if there was enough internal friction to cause a drop in mileage?

 

There wasn’t in my BILs truck. And all the main and rod bearings were worn. It just ended up seizing up, but sounded fine until then. It did struggle to start like the battery was low.

 

Interesting. Did his mileage drop?

 

Wasn’t dailying it and checking at that time.

 

There's a lot of denial in this thread about bearings going out causing issues. On a completely different powerplant (a Toyota 2JZ engine) I had a few weeks ago a bearing go out. The truck kept running and even drove home, no bad noises or anything, but it started running rough and oil pressure was behaving weird. Initially as I got a mile down the road there was a weird feeling, the truck still had plenty of power but it was like the there was more drag on the truck and it wasnt as effortless to maintain speed as it was before---ever so slight I thought I was insane so ignored it.

I don't post this to scare OP, but to make a point to that a bearing slowly degrading could certainly have slowly building issues and cause more resistance on the drivetrain. Mine completely catastrophically failed (you can see a sliver of metal hanging out on the right half) and it still ran and drove home, and I didn't know what was wrong or what the issue was until I fully took the engine apart.



With all of that said, OP it's probably just the winter blend of gas and big tires and a lift. I wouldn't worry about it.

PS don't reuse your rod bolts because you're lazy/cheap

 

Without links to your " many reasons" ......it's just noise

 

LOL, you do have a basic understanding of how engines work, right? As @snivilous said above, if you increase the resistance and friction of the rotating assembly, the gas mileage WILL suffer. Test it out, put some 20W50 in there and see what happens to your MPGs.

 

All good. Lived n Toronto/ Bradford for 5 years till I found out my the woman ( absolutely beautiful woman) I was with was married the worst serial rapist in Canada history! His ex wife. Found out she took a plea deal and I never knew. Google Selvia Kubbiah. Actually a movie about it but used a fake name for her in the movie. Can’t make this shit up. Toronto sun did many articles about it.

 

Other than the response above of living in Canada years ago engaged to a nut bag with a crazy history, all info was after lift. Same drive , same Cruze control set, same gas station. Yes- maybe full but a 6 mpg drop is weird. Reset trip
Every time and all after the lift.

 

Headwinds can make a big difference as well.

 

Your gas milage WILL suffer from a low tire, a hill, a wind, a heavy foot, a load, 4X4.....it's not always a main bearing, could be a multitude of things

 

A combination of things. Wind, winter blend gas, colder temps makes the air more dense hence more air resistance, less traffic. More traffic your in less air resistance you will experience.

 

Exactly. I didn't say it was the ONLY reason....I said it had been stated as A reason.