My best commute mpg ever ... why!?

Discussion in 'Gen 2 Prius Fuel Economy' started by Ichiro, Jul 11, 2008.

  1. Ichiro

    Ichiro Member

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    I have ~6000 miles on my Prius, bought in April.
    Since April I've been averaging about 42mpg, low = 40, high=45.

    At ~4000 miles a few things happened at once:
    - I had to replace one of the Integrities, so I now have one Pirelli P3000 in the front.
    - First oil change,
    - 4 wheel alignment.

    I didn't notice much change in mileage and figured that the mis-matched tire was cancelling out any improvements from the alignment. I did notice that the car was much more stable on the highway in high winds.

    Today, without driving any differently on my normal commute, I suddenly got a big jump in mpg... almost 50! I'm hoping it keeps up, but I'm not sure what exactly changed all of a sudden.
     

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  2. TJandGENESIS

    TJandGENESIS Are We Having Fun Yet?

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    Weird.

    I got a huge spike last night, and in my HyHighlander. I am not sure what cause this, short but sweet MPG:
     

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  3. dehati

    dehati New Member

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    I get about 49 mpg driving in cities.
     
  4. bmg21

    bmg21 New Member

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    From what I've read on the boards here, it seems around the 5k mark the engine breaks in and you start to begin to see better gas mileage. You could be figuring out how to drive the car as well. Quite a bit can come into play. I'm surprised your down around 40's though. Are you taking all short trips or going way over the speed limit? Could be alignment as well. Heck I'm a new prius owner too and drove 70 mph from the cities to see what kinda mileage I'd get and it was still at 50.2 over 80 miles. Not sure what your doing wrong with getting 40. Keep plugging away though!

    B
     
  5. donee

    donee New Member

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    Hi Ichiro,

    The Oil Change and alignment are most likely the causes. The initial oil put in at the factory is a special formulation for breaking in the engine. So, its probably higher viscosity. Additionally, if it was much above the top dip stick mark, there might be a little mileage hit from that. If the refill is now standard 5W-30, and 1/4 inch below the top dipstick mark, that will help a bunch. Let alone, that the oil run for 5000 miles in a new engine is going to be loaded up with fine materials from the break-in process.

    When my car was new it was acceptably stable on the highway. I drove back in mild winter winds from the dealarship 484 miles. No problems. If you had problems with trucks pushing the car around in an uncontrollable fashion, it was probably an alignment issue. Which might result in more rolling resistance.

    The new tire would cause your mileage to be less. The new sharp edges on the rubber have higher rolling resistance, and the side walls do not flex as readily on new tire.
     
  6. N3FOL

    N3FOL Member

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    I am just wondering what happened to your tire. :confused:

    I tend to get nice mpg numbers right after an oil change. Keep your speed at posted speed limit and you'll see your mpg improve.
     
  7. Sheepdog

    Sheepdog C'Mere Sheepie!

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    it's a new car. why wouldnt the dealer give you a matched tire?
     
  8. PriuStorm

    PriuStorm Senior Member

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    I asked this question previously because when we drive south from Sacramento to Bakersfield, we had about 8mpg better fuel efficiency on the way down than on the way home.

    The consensus from the forum was that a subtle tailwind did the trick (which turned into a headwind on the way back).

    So, maybe you had a tail wind and didn't realize it. :)
     
  9. morpheusx

    morpheusx Professor Chaos

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    Wait until you hit about the break in at about 30,000 miles.
     
  10. Ichiro

    Ichiro Member

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    Got a big nail in one of the original Goodyear's that wasn't repairable ... at the time I was stuck at America's Best Tires who did not have the Integrity in stock. So I went with the Pirelli P3000.

    I think that I have to consider that my driving style has also changed considerably since April. I drive much more slowly now...
     
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