fuel economy

it will go back up if you take out the excess

 

Tara,
There can be many factors. You haven't posted your location in your profile so I don't know if temperature is a factor. Since you mention both 5K and 10K service, I presume some many months passed between the two and the 10K was fairly recent.

One partial factor could be the switch to 'winter formula' gas in some areas. Less energy available per gallon.

Tire pressure will decrease as the temp drops. If you set them at 35/33 at 70F they wouldn't be anywhere near that at 0F. I set mine at 38/36 though when it was about 32F and I knew it was going to drop below 0F, I set them at 40/38 to account for 'shrinkage'. I don't know the MPG drop per unit of pressure drop.

In Oct, when my car was brand spanking new with temps in the 40s to 70's, my normal weekly driving yielded mid to high 40s. As the temps dropped the MPG went down to low 40s. When it was -9F and I drove to Montreal - a lot of interstate, it was about 38.

2 weeks ago when I came up from Middlebury after accidentally resetting the MPG screen, I got 57.8 for 31 miles at 54F. This road is ideal for Prii, max 50 MPH, few stops not too hilly and EV possible the last few miles in slow construction traffic.

 

possible that the dealer put in the wrong weight of oil 10-30 or 15-40 instead of 5-30. Dirty air filter, winter gas? not sure they use it in Ca. but it's a possibility. You haven't hit a curb or bad pot hole and knocked the front end out of alignment? Running the climate control in Auto and having the A/C going when not needed? Changed jobs and have a much shorter commute that doesn't alow the ICE to go into full hybrid? many possibilities

 

EPA is now testing Classics re. economy and tailpipe emissions. My son got a call from EPA who wanted to test his car in a 24 hour test. They installed sensors, a GPS unit with a big box sand 2 batteries in his trunk. During the test, he had a flat tire and had to remove the stuff from his trunk to get the spare. He had to buy a new tire. Upon completion of the 24 hour test, EPA removed the equipment, gave him $75.00 and an additional $50.00 account the tire trouble.

 

even in san diego, you will undergo winter formula gas due to the seasonal weather patterns that trap more polution.

only very small parts of Texas, Louisiana, and Florida dont switch.

 

I only get 43.5 mpg. Why aren't I getting what some others are, like 55mpg?

 

Your MPG will increase when you get more mileage on the car. 15K miles is about when you can start getting 50mpg on a normal basis without having to baby it too much.

low to mid 40's is normal on newer cars under 15k miles.