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2008 Prius MPG issue

Discussion in 'Newbie Forum' started by Beckerp360, Nov 30, 2012.

  1. Beckerp360

    Beckerp360 New Member

    Joined:
    Nov 29, 2012
    1
    0
    0
    Location:
    Seattle, Washington
    Vehicle:
    2008 Prius
    Model:
    Five
    @ 59+k the 205-45 17 Toyo Z rated tires on my 2008 Jet Black model 5 needed replacements. Since they were lousy the few times we had snow I replaced them with Bridgestone Provendas (G019 Grids). We noticed some excessive wear on the inside of the rear tires and too it in for a 60k mile check at the dealership and asked to have the alignment checked. Since it is 80 miles to the nearest reliable Toyota dealer where it has been serviced it had nearly a week of driving and some 400 miles on them before we could get an appointment. MPG was at the same 46-48 Mpg we had averaged for 45k since we bought it before the tire change as after. It did feel a little lighter on the handling with the new tires but nothing outstanding.

    The dealership ave me the expected line amount "solid rear axles are unadjustsble" line but said they had "adjusted to front to "match the rear"".. With throttle body cleaning I expected no changes.
    The car now gets 40.5 mpg ... When I took it back they made " minor changes" and the mileage dropped to 38 mpg 40.5 mpg on the highway!

    Clearly it is going back again but the tech's wanted me to run a tank of gas and the fill/mileage check to verify the lousy mileage ... Saying the dash indicator was a " estimate" .... So I am...grudgingly.

    The low profile (45) tires. On 17" wheels did 46-48 mg for 5 years so that is not the problem ant the Toyo's went 59k miles so tere was not a problem.
    Any Ideas why the sudden and dramatic mileage drop after it had been fine mpg wise with the new tires for 400miles and the alignment spec says it is "adjusted correctly "?
     
    #1 Beckerp360, Nov 30, 2012
  2. ewxlt66

    ewxlt66 Active Member

    Joined:
    May 1, 2008
    535
    186
    0
    Location:
    Dana Point, CA
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Wow. That's a frustrating situation.
     
    #2 ewxlt66, Nov 30, 2012
  3. F8L

    F8L Protecting Habitat & AG Lands

    Joined:
    Aug 14, 2006
    19,011
    4,081
    50
    Location:
    Grass Valley, CA.
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Post the alignment sheet if you can.

    Did you check the air pressure in the new tires after they worked on it?

    Also check the 12v battery voltage with the car off and having sat for 4+ hours. It should be at least 12.4v. Sometimes the dealer will open the doors and let the car sit for a long time which can drain the battery. If you are still on the original battery it could be on its way out.

    There is also the chance that your new tires are not as fuel efficient as the old ones. You may have had good driving conditions during that 400 miles which masked the loss. The tires you purchased are not low rolling resistance rated.
     
    #3 F8L, Nov 30, 2012
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