Lowered mpg after dealer visit

I look at the individual trips, the instantaneous readout, the tank average (all from the computer) and I do the math at every fillup. The tank average from the computer and from the doing the math at the pump have always been within .5 mpg. (One half of one mile per gallon)

 

Cold weather makes a fairly big difference, especially during the first several minutes after you fire up. Once the truck is up to normal operating temp, not so much. If there is snow or ice on the road, that has an impact. Cold air is denser than warm air, so there is a slight increase in atmospheric resistance. Cold also effectively reduces the air pressure in your tires, increasing rolling resistance.

That, combined with the fact that the dealer let it idle for an hour is why your mileage was down for that tank.

 

I had the same thing after my rear-diff maintenance. My mpg on a given trip dropped like 3-4mpg for a couple of weeks. Then it slowly came back to normal.

For that, though, my truck was at the dealership for 6 weeks.

 

WOW! This thread just saved me a lot of time...I just had my 10k service and the ECU was updated. My mpg has been 17ish, it is usually in 19-20. Now I know it's nothing to be worried about and I'll give it a couple hundred miles and see if it improves.

Thanks guys!!!

 

I thought it was clear in my post....the computer is telling me 22ish tank averages and dividing the miles driven by the gallons I out in are coming out at 17 sometimes less.

 

You didnt specify it was your mileage of 22mpg being 17mpg. I thought you were making a general statement of the trucks in total only being good for around 17mpg

 

wow, i wish i could get that much, mines gotten 15 since i got it, god knows whats gonna happen when i service it at 10k

 

The MPG display on my dash had been consistant around 22MPG. A trip to the Barnegat Lighthouse got me 26MPG. I took the truck into the dealer a few weeks ago and had them do my first oil change at around 1500 miles. I do this with all my vehicles. After getting it back from the dealer and running a tank full of fuel, my dash computer says I'm getting 14MPG. I thought something fishy is going on. My 2005 Nissan Frontier 6cyl 4.0 got this kind of gas mileage (14MPG). I was excited when my Tacoma was getting 22MPG. We'll see what happens I guess.

***UPDATE*** I noticed there are 3 things that show on the dash when you shut the truck down (never seen this before, my son pointed it out) one of those things was "MPG per tankfull of fuel" something like that. It said I was getting 19.6MPG. That makes me feel better.