I notice a pretty significant MPG increase since I passed about 800 miles. Up until then I was getting around 17-18 MPG mixed driving mostly highway. Since then i've put on 300 or so miles and my mileage is up to about 22, right at the EPA est MPG for my 3.3 L 4x4 for the same mostly highway driving. Is this typical?

 

I didn't notice any improvement in gas mileage in any one of my cars from 0 miles to 200 miles to even 1,500 miles.

I think you're just getting used to it.. it's like renting a car, sometimes your rear tires spin because it has so much power so you kind of train yourself on not to do jack rabbit starts.

 

Possible or maybe the computer on the truck learned my driving habits. Weather is another factor also, since it is not 20 below 0 anymore.

 

You're not going to get 4 or 5 MPG more because the computer learned your driving habits. You will see 4 or 5 MPG more because YOU adjust your driving habits.

 

I will continually stand behind my theory that a broken in motor and drivetrain is not netting 5 mpg gain.
If so, we need to stop complaining about oil. Oil was thinned out to help reduce drag. We add in thicker oil yet nobody ever says "I used the oil I think is better and lost MPG".

I can't explain why you are in the positive by 5, that's dramatic. And, 300 miles is a very short distance to have such an extreme case.
For only 300 out of 800, the current MPG would be very dramatic if you altered a 17mpg into 21 mpg. It's still an average of 1100 miles to get to the 21, meaning you are probably in the upper 20s.

Could be that the 'newness' is worn off and you aren't driving it as hard. Could be the wind shifted and you've had more tailwind. Or your tires are overflated. Or winter gas is gone.

 

Only hand calculated matters.

 

Mine starting getting better mileage when the temperature warmed up outside.

 

Most places are coming out of winter.

Vehicle begins warmer, spends less time running rich/in open loop, spends more time operating more efficiently at temperature.

Tires tend to be better/more highly inflated when it's warmer as most people don't watch pressures closely enough.

IDK if winter gas is changing to summer gas yet or not, or where, but that is a thing also.

People stop idling their cars to warm them up not thinking about the effect on mileage.

 

I would not worry about mpg the first couple of tanks… I would - after I got home from the dealer, install a fram ultra for the first oil change. This one is 20 micron 99% which is a little tighter than the factory filter. I also immediately install a strong magnet in the drain plug. Epoxy it in there.. this will pick up iron that may pass through the filter. And YOU will know if there is “wear-in” still going on two or three changes later… there is just NO WAY I would have 2 ball bearing turbos and not have a magnet on duty to see how things are going..

 

As long as you are comparing apples to apples, the readout is likely to be less math error prone…

As long as you are aware remote start warmups aren’t counted in the mileage calc from the display.