Gas mileage - temperature vs. break-in period

[pyccku]

We got our Prius in May. We've been averaging about 46-48mpg with the a/c running most of the time and 5 people in the car. Average temps 100-110.

I just hit 5000 miles last week. The temperature has also gone down to high 60's on the way to work, low 90's on the way from work. Now we've averaged 53-55mpg the past two tanks.

I'm guessing that the big jump in mpg is due to the temperature going down quite a bit, and maybe a little bit of the improvement is the fabled 5K mileage break-in period. Does this sound like a reasonable explanation? So I can expect to stay a little higher now that it's broken in, but expect a drop in mpg come April when the temp goes up again.

[efusco]

sounds reasonable. also your familiarity with the car and increasing efficiency in driving it. You're doing quite well for having so few miles.

BTW, this is a good time to check your tire pressure since temps are dropping.

I'd neglected mine for a couple months and usually keep them at 44f/42r....when I checked today I was down to 40f/38r.

[TonyPSchaefer]

Yeah. I'm voting on both fronts.

[Bob64]

Higher temps are usually better for mileage... unless you use the AC.

[FL_Prius_Driver]

The real sneaky change will be in your driving habits. They change slowly....but they do change.

[viking31]

<div class='quotetop'>QUOTE(pyccku @ Oct 1 2007, 09:18 PM) [snapback]520088[/snapback]</div>

We got our Prius in May. We've been averaging about 46-48mpg with the a/c running most of the time and 5 people in the car. Average temps 100-110.

I just hit 5000 miles last week. The temperature has also gone down to high 60's on the way to work, low 90's on the way from work. Now we've averaged 53-55mpg the past two tanks.

I'm guessing that the big jump in mpg is due to the temperature going down quite a bit, and maybe a little bit of the improvement is the fabled 5K mileage break-in period. Does this sound like a reasonable explanation? So I can expect to stay a little higher now that it's broken in, but expect a drop in mpg come April when the temp goes up again.
[/b]

46-48 seems to be fine with 5 people in the car. I have averaged just right at 50 MPG with mostly myself, about 70% or so Hwy at 70 to 75 MPH with the rest being slower back country roads.

I keep very close tabs on my mileage figures and looking back at my spreadsheet (I have 50,000 miles on the car now) I did not see the so called 5,000 mile improvement at all. The mileage has been very consistent throughout the life of the car. Even if the 5,000 mile break in point existed it would be very gradual and perhaps hardly noticeable.

The five main factors that affect mileage most predominately for me are (in no particular order): tire pressure (I run 44/42), outside temp (higher is better to a point; then A/C use increases at higher temps and can lessen the positive effect of higher temps fuel mileage), passenger load (my family of five with full groceries and max A/C on a hot summer day keeps the gerbils under the hood running at full speed!), average speed (closer to 40 MPH or so seems to get the best mileage), and wind direction.

Rick
#4 2006