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Renegade: sudden loss of gas mileage

Discussion in 'Compacts: Renegade, Patriot, Compass, Caliber' started by NeilG, Aug 1, 2020.

  1. NeilG

    NeilG New

    Feb 6, 2009
    I’ve got 28,000 miles on my 2018 renegade which has the 2.4 and the factory tow package.
    According to the gauges I was getting around 28 miles per gallon.
    That has held very steady. About a month ago I noticed It’s dropped down to 24 miles a gallon.
    It’s had a recent oil change and it runs well.
    I have been running the air conditioner a lot but I bought the car last August and I ran the air conditioner a lot then as well getting my usual 28

    It might be paranoia but it’s sort of seems the car slows down more than it used to when I take my foot off of the gas. If I had a caliper dragging I would smell that distinctive smell burning brake pads and I don’t.
    No particular wheel feels hotter than the others after a long drive.

    Any ideas? Could it be a transmission issue? I suppose I should jack the car up and spin each wheel around and see if they feel nice.
    Any ideas would be appreciated
  2. ImperialCrown

    ImperialCrown Moderator
    Level III Supporter

    Jun 8, 2008
    Is it the factory recommended viscosity and material standard motor oil? A heavier oil will slow the valve lift/timing hydraulics and add to mechanical viscous drag.
    An API-certified, 0W-20 meeting MS-6395 is the spec. Synthetic is optional and is up to you.
    Is it shifting as before?

    There is an updated PCM version (TSB # 18-054-20) that came out this past week that replaces this one (TSB # 18-043-19):
    It doesn't specifically address fuel economy, but you may notice a difference?
    DC-93 likes this.
  3. AllanC

    AllanC Well-Known Member

    Jan 6, 2003
    I would look at the fuel trim values (short term and long term). If they are very negative and not oscillating around zero % then there is a problem with excessive fuel system pressure or 1 or more injectors is dumping more fuel into its respective cylinder when activating. This is causing an overly rich mixture and the fuel management system is trying to correct by taking away fuel (negative fuel trim). An overly rich fuel mixture can contribute to increased fuel consumption.

    Is the transmission shifting through all 9 gear ratios and is in 9th gear when driving on the highway? You can pull the transmission selector lever down and to the left when in DRIVE position and you will see a number illuminate on the instrument panel indicating current gear being used in the transmission. If the transmission is in a lower gear (not 9th) the engine will run faster for a given highway speed and thus consume more fuel.
  4. DC-93

    DC-93 Well-Known Member

    May 1, 2014
    I think any 0-20W oil is synthetic. Not sure if it's possible for a regular oil to get down to 0. (but I'm not a chemist!)

    My 18 Compass has the 2.4 and when I get my Pennzoil jug, it's synthetic.

    I turn under 2K rpms on the highway at 75. I get around the same MPGs as the OP: 28.
    gforce2002 likes this.
  5. bguy

    bguy Well-Known Member

    Dec 9, 2007
    Are you getting to high gear?
    Could your park brake be not fully released?

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