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Observed Increase in Fuel Efficiency For the 2012 Prius

As the 2012 Prius was approaching its 120k mile milestone, I noticed a dip in fuel efficiency among other issues (cold start rattle, struggling acceleration, rough ride). In its glory days, I was getting and average of mid 50’s MPG on a full tank. On rare driving circumstances, I was able to bump that number to beyond 60 MPG. Ever since I was putting large amount of miles to the Prius strictly from commuting in the last 2.75 years (about 26,500+ miles per year), my MPG dipped to the mid 40’s. This and the fact that the Prius has accumulated close to 120k miles prompted me to take the car to a local Toyota dealership for a full servicing. In return, the dealership gave me a laundry list of recommended high mileage maintenance service.

Using their list provided, I maintained the Prius myself and saved over $1,500 and made a note of observing changes in fuel efficiency. These are the services I performed on my Prius at around the 120k milestone:

It has been two or more months since I’ve performed these services and I have noticed a gradual rebound in fuel efficiency. I’ve been getting a constant 45-48 MPG prior to the service, driving solo 99% of the time towards the tail end of October 2017. After performing the services, I am pleased to say that I have been hitting averages of between 54-56 MPG – this with two adults and a 16 month old driving.

My next maintenance will include cleaning the complete EGR system, intake manifold and oil change at around 125k using Mobil 1 High Mileage 0W-20. I am eager to see how these maintenance services will further affect the overall MPG average of the aging Prius.

5 comments for “Observed Increase in Fuel Efficiency For the 2012 Prius

  1. Dusty Bottoms
    March 24, 2019 at 6:11 AM

    I completed this list except except for cleaning the fan in about 5 hours. This included plentiful breaks for beer, cigars, food, bodily functions. Not bad earning over $100/hr for my labor! Thanks for these awesome tutorials!

    • March 29, 2019 at 2:38 PM

      5 hours is great timing, glad you found the DIY guides helpful!

  2. Anonymous
    March 28, 2018 at 11:58 AM

    Thanks for the DIY list. I will try to tackle some of these in the future. I’m approaching 60,000 miles on my 2015 Prius. Would you recommend doing any those these services for 60,000 miles?

    I purchased the Prius certified used about 2 years ago and ever since then, I have been getting an average of 48 mpg. Will doing these help increase the mpg?

    • March 28, 2018 at 1:26 PM

      You’ll be fine at 60k miles unless you plan to ramp up the annual mileage anytime soon. The spark plugs are recommended to be changed at 120k, which is what I did, although you can change them out as early as 100k. Some Prius owner change their automatic transmission fluid at 30k, then every 60k after. I changed mines at 120k and plan to do it every 60k thereafter. At 60k miles, I think the services that would make the most impact on fuel efficiency would be cleaning the intake manifold, cleaning the complete EGR system, replace PCV valve, cleaning the hybrid battery fan, oil change and automatic transmission fluid change. Inverter fluids exchange isn’t necessary until 100k miles. In addition, temperature, distance, MPH and variation of terrain on routes traveled also affect overall mileage.

      • Anonymous
        March 28, 2018 at 1:44 PM

        That’s a long list. Lol. Thanks for the reply!

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