First 50 miles

The first few miles appear to affect the MFD MPG more but it like your college GPA a few C and D that first Freshman semester when you are getting you feet on the ground take a lot of B and A to pull up by the time you are applying to grad school. The low MPF the first 5 or 10 min with a low number of miles on the tank pulls the MFD figure down faster that average or higher than average build it back up. Also as you burn gas the car gets lighter so you will get better mileage. My typical pattern over the last year and a bit is that I fill up on the way home. Warm car. Air temp close to the high for the day. Lots of down hill between there and my house. I park basking in the glow of 70-80 mpg figures. Then morning comes. It is a lot colder out side. The car is cold. For the first 5min bar on the consumption display I am around 25 mpg and my Tank miles are down to 40’s. They bounce around for the first ¼ tank then slowly rise to something in the 50’s. Now with addition of my block heater the first bar is up because the car is warm but the overall pattern with a new tank is the same start low, bounce around then rise through the rest of the tank

 

hdrygas is right. And it makes perfect sense. Think about how it calculates (or how I would presume it calculates).

1 - It knows the rate at which fuel is flowing
2 - It knows how many mph your are driving

So, Let's say every second it takes a sampling. The fewer samples you have, the more each individual sample will affect your mileage. As you keep adding miles, adjustments will be much smaller.

For example:

Example 1 (5 samples): 50mpg, 50mpg, 50mpg, 50mpg, 25mpg
Average of example 1 is: 45

Example 2 (10 samples): 50,50,50,50,50,50,50,50,50,25
Average of example 2 is: 47.5

So, let's say you had 500 samples. 100 at 20mpg and 400 at 60mpg. Your average would be 52! It's all about averages.

hdrygas's example of college is good, but if you only got a few C and D's and the majority of everything else were A's and B's, then your average would be up towards the A's and B's.


EDIT - I should also add - it can have the opposite effect as well. If you start of getting 60mpg in your first 25-50 miles, you could still end up with 50 when you fill up. I had a nice little drive one day in my first 26 miles that had me up to 64.2mpg. Then my next leg of my trip, I dropped down into the 50's. Final reading was 54.3

 

Have you actually validated the MFD's mileage stats with reality? IE, how many miles did you get on your fillup of X gallons? I've noticed sometimes the MFD is quite a bit off (anywhere from 1-3 mpg).

 

Well.. that's certainly odd. I am at over 200 miles and still am able to increase my mpg a bit. From 50-200, I went from 49mpg to 52.

 

My first 50 miles have nothing to do with what I get for a tank. Some times it goes up a lot, other times it goes down. Mostly depends on car temperature when I fill and where I am driving.

I've had 50 miles at under 40 and 50 miles at over 70. My tank average generally comes out 50 to 57 in summer regardless.