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05 Acura TSX Gas Mileage

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  • #576142
    inxsinxs
    Participant

      My TSX is my daily driver with 138K miles and a manual transmission.

      My commute to work is 17 miles each way (20 minute drive). 14 miles on interstate going ~70 mph. 3 miles of lights where the speed limit is 50 (maybe 10 lights with 2 stops). On a full tank, I get 300 miles and add 13.5 gallons. So I am getting 22 mpg, which is not good IMO for my commute. I have had low gas mileage since I bough the car with 97K miles. On my occasional long trips, I get around 400 miles to a tank (~31 mpg).

      I would consider myself an advanced DIY mechanic and want to figure this out. I am pretty sure I have watched every ETCG repair video. I read through the poor mpg as well on this site.

      I have no CEL. My spark plugs were replaced at 110K miles with NGK plugs on the sticker under the hood (iridium plugs, IIRC). I change the oil every 7500 miles with Castrol syntec (or edge). I used regular oil on my first oil change, and I was losing oil. Mobile1 gave me the same problem. Honda MT fluid and the clutch is new.

      I cleaned the slide pins on the brake caliper and used silicone grease. I cleaned the stainless steel clips with a dremel/wire wheel. Cleaned the part of the pads that slide on the clips. Used a bit of anti-seize on them. Pads were evenly worn, with the outside pad material a bit lower than the inside. When I first got the car, the pins were stuck, so the rear rotors do not have a smooth surface, but I was able to free them up and replace them when the weather was warmer when I lived up north.

      Tires are Michelin MXV4 (OEM was MXM4), so similar to OEM with plenty of tread. One of my tires has a very slow leak that firestone couldn’t identify the leak.

      Sorry for the long post. Wanted to be thorough. I bought a bluetooth OBD2 and have the free version of torque on my droid. I suspect I will buy the full version to get more capabilities.

      What should I do next? I appreciate any suggestions.

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    • #576160
      college mancollege man
      Moderator
        #576309
        EricTheCarGuy 1EricTheCarGuy
        Keymaster

          You’ve done your homework. Thank you. Honestly though, I think you’re doing pretty good at 31mpg. You also need to consider that the faster you drive the more fuel you will use. I think the highway mpg ratings are based on 60mph. There’s a lot more wind resistance at 70mph. Also, winter fuel is more volatile than summer fuel. As a result you will use more of it. In addition, if you’re letting your car warm up before your drive, you’re burning fuel which will effect your mileage.

          In short, there may be nothing more you can do. Keep us posted if that’s not the case.

          #576363
          inxsinxs
          Participant

            Thanks guys. I’ll keep you updated.

            The 31 mpg was when I would drive from IL to PA, so ~500 mile trip. That was a rare trip.

            The 22 mpg is what I get on my normal commute to work. I live in Houston where we average 12 hours a year below freezing temperatures, so my car doesn’t need to warm up. I start the car in the morning and drive immediately to work.

            #576479
            PaulPaul
            Participant

              I have an 08 TSX with an automatic transmission. Coincidentally, I also have a slow leak with one of the OEM wheels.

              What octane are you using? I typically get ~23 MPG with 87 octane while driving 50% city and 50% highway, and I have noticed an increase to ~26 MPG when using 91 octane. The TSX has a high(ish) compression engine. It will run with 87 octane because the ECM can retard the timing, but the car is a bit sluggish. With 89 or 91 octane, the fuel efficiency increases noticeably and the performance improves. I haven’t noticed a significant improvement with 93 octane over 91 octane though. Also, reformulated gas has been mandated where I live for 15 years now. I’ve consistently obtained ~40 MPG over a long trip cruising at 70 MPH with 91-octane, non-reformulated gas.

              Also, is the AC set to automatic? The climate control system has 3 AC settings: forced on, forced off, and automatic (which has no indicator light on the climate control panel).

              Finally, does your car have the plastic, under-engine splash shield? TSX owners on another forum noticed a slight decrease in fuel economy with the splash shield removed. It seems as the splash shield guides air underneath the car to improve fuel efficiency.

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