Dropping mpg

About a month and half, my mpg went from 17.2 to 16.8.
This week they replaced the alternator and fan clutch and for whatever reason reset the mpg meter.
Now it’s only gotten up to 15.6 mpg. Is there a reason why mpgs are dropping?

 

Truck forgets everything when you reset the battery. It has to relearn how you’re driving, and the lifetime fuel economy meter was totally lost. I’m sure it also sat idling after the alternator was replaced. Idling is getting an mpg of 0.

The only reason you would need to be concerned about anything is if your tank averages change significantly.

 

do you think it will take about a week to get it back to what it really needs to read?

 

15.5 is about all I get, if we're talking combined city/highway average.

 

I was getting 16.0 mpg up until a couple of weeks ago. Gas mileage dropped to 15 mpg. I thought I got bad gas.

Then I remembered that every year in the fall in this region, they start using a "winter blend" gas that is more oxygenated in order to reduce emissions when there are air inversions.

This results in 1-2 mpg less efficiency every year starting in late September.

But, seems like it may have been introduced earlier this year.

 

I get 13.9

 

Why don't you hand calculate it? The truck estimate is notoriously inaccurate.

 

Oh wow

 

I feel like an idiot bc I only get 12.9

 

Well, I work from home and I hardly ever hit the highway - I get somewhere around 12 +/- 0.5

 

I stand corrected..

 

You guys are doing it wrong. My MPG went up after I disconnected the battery, reset mine and jumped on the highway immediately after.

But really, I wouldn’t worry about it. The reset is likely the cause and that MPG is not abnormal for the Tundra. Our Sequoia is around 13.8.

 

^^^This. Same thing with "Range" estimates. Mostly useless.

Dan

 

It's great to get a ballpark figure. Remember, it is often labeled as a "cruising" range. That means going on the highway at certain speed. If you drive around town half the tank, of course it will be inaccurate.

 

My MPG monitor is very accurate. When I fill the tank, I can get the gas level to the exact same spot in the filler neck every time. I was amazed how accurate it was; down to the tenth of a gallon.