Tag Archives: hybrid

why is my hybrid mpg getting worse with time?

I have a 2007 Toyota Camry Hybrid with 35,000 miles. The MPG has decreased from 34.5 mpg for the first 10,000 miles, to 32 mpg by 20,000 miles, and now is 30 mpg at 35,000 miles. My father analyzed the online database for Toyota Hybrid mpg, and found that the median MPG got BETTER with mileage, from 35.4 mpg initially, to 36.1 mpg at 10,000-20,000 miles, to 37.9 mpg at 20,000-30,000 miles.

My MPG matched the reports of others initially at 34.5 mpg, but is now at 30 mpg, WAY below the 38 mpg reported by others.

Do you have any idea what might be going on? Many thanks for any suggestions!

Here is some more information that might be relevant:

I purchased the vehicle mid-January 2007. My driving routine changed in May 2007, but has been fairly constant from there. I am driving in Southern California (San Diego/Riverside County), with my typical commute about 20 miles each way. With errands this typically works out to about 50 miles per day, driving typically the same week to week. On average, I probably do one longer drive each week, to Anaheim or San Diego from Fallbrook, about 80 miles each way.

A plot of my MPG vs. time, with all fill-ups, is here.

A plot of my MPG vs. mileage, selecting only fill-ups after May 2007 that have an average of 50-80 miles per day, to eliminate unusual driving patterns, is here.

Thoughts we considered are:

  • A/C Econo mode was turned off last summer and not turned back on. I always drive with the air compressor running, so there should be no difference for seasons, other than it having to work harder in our “extreme” weather. I’ve run for a few tanks with the econo mode on and have not found any difference.
  • I installed a ham radio antenna on the car in October 2007. No difference in mpg noted.
  • Driving habit change. When I first got the car, I was driving to squeeze every mile out of it possible as it was new and interesting, and eventually the novelty wore off. I have tried driving recently paying more attention to my driving habit, trying to squeeze every mile out of it again, and there seems to be no detectable difference.
  • Bad Oil. Toyota of Temecula Valley put the WRONG oil (higher viscosity non-synthetic) in my car for its first oil change 3/23/07, which was drained and replaced within a few days. There was a really bad dip immediately, but it didn’t cause a permanent decrease in MPG. I would expect any MPG decrease from this to eventually go away with time, and not continue to make things worse.