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Acura RDX Fuel Efficiency Concerns



  • frog22frog22 Posts: 21
    does anyone know if using reg gas will damage the engine, or create any other problems? I saw on Acura's website that they prefer premium fuel but that you can use there a downside to this?
  • ringzringz Posts: 1
    Yes, you must use premium. You can put the cheaper stuff in every once in a while, but long use of <91 Octane will damage the engine.

    I have had my RDX for 2 weeks and am getting 23.9 MPG for highway and city. I don't engage the turbo too much and use the AC in the afternoon/evenings. However, I also live in Florida so I don't deal with mountainous terrain.

    Take it easy on the pedal and avoid the hard brakes and you should get 380-420 miles per tank. Good luck!!
  • jc261095jc261095 Posts: 3
    Just to give a little more info about using premium fuel. Acura says that the care is tuned for premium but you can use other levels. For the TL, TSX even the MDX this would be ok. It is the Turbo in the RDX that makes you use the premium. It is all related to the Compression Ratio. Most cars will be around 8:1 and they run regular. The RDX says it has a ration of 8.8:1. Most high performance cars that need premium are around 10:1. If you did not use the turbo in the RDX at all you would be ok with a lower octane. However you will get better milage with premium. To restate frog22 "You can put the cheaper stuff in every once in a while" if you have to but best for the engine to keep with the premium.
  • I know the Max. Towing is 1500 Lbs for the RDX but does anyone know how many Lbs the RDX could carry with inside. I heard the Turbo Engine couldn't carry much heavy stuff. Is that true? I like the car but never have any idea about Turbo Engine. The mileage for 2008 RDX is 17/22 which is really close to the MDX, why Acura will use the 4 cyc. instead of v6 if they get the same mileage? What is the advantage and disadvantage for the turbo engine?
  • rich4jrich4j Posts: 12
    I was at the dealer today asking about having to use premium

    I know a sales guy will say whatever it takes to sell but his message was that the mechanics say if you put premium in every now and then ...(maybe every fifth fill up) you should be fine.

    Only an issue when you start getting over 50K, 60K etc...

    Sounds like fiction to me?
  • wwestwwest Posts: 10,706
    The worse that can happen to your engine from the use of regular fuel is a low level of engine knock/ping until the ECU figures out the correct A/F mixture to prevent knock/ping and also adjusts the shift pattern accordingly to prevent knock/ping due to engine lugging.

    In the end the A/F mixture will run a bit on the rich side and the transaxle will be a bit quicker to downshift and/or not so quick to upshift into the next higher gear.

    The monetary result....???


    But you may very well burn enough "extra" regular fuel to make up for the money you "saved".
  • wwestwwest Posts: 10,706
    thought about hard-wiring the turbo wastegates into the fully open position??

    IMMHO the FE could be improved dramatically if the driver could somehow choose when the turboes are to be used, say not prior to 2/3's throttle or only with RAPID gas pedal depression.....
  • The under-powered CR-5...wife got's a good car and good gas mileage...I liked it but would have preferred the Turbo fired Acura....even with a little less gas mileage...Hell, my 04 Vette gets 28 on the highway at 80mph :)
  • I am getting horrible gas mileage on my 2008 RDX. Is anyone else experiencing the same thing. Two of my friends bought RDX's at the same time and they are getting 18-21 mpg. I am getting 13 mpg and I drive like grandma. I am mostly city, but so is one of my friends. We are going to swap cars for a few days and see if there is a difference.
  • angelina247angelina247 Posts: 17
    I don't know how many miles you had on your car when you first wrote, but I have had my car a few weeks now and am getting better mileage than I did in the beginning (17.1 city now). I was initially getting about 13 miles per gallon. I hear you should get better mileage after 600 miles or so. Also driving too slow will actually give you less gas mileage, especially in the beginning . Something about "blowing out the engine" which will increase gas mleage. I'm sure someone on the board can explain it better than I can.
  • mark4490mark4490 Posts: 16
    I've only had my RDX for 3 weeks and I've only driven 1100 miles, but I'm getting ~20mpg. I think the other person that responded it right about not driving too slowly. A vehicle has it's maximum efficiency at a certain speed, say 60 mph. Go slower or faster and you're wasting gas.

    When I'm going up mountains or steep hills (i.e., Mt Tam in Marin), the fuel economy drops to almost zero when I'm going too slow. So I give it gas more gas to speed-up and my fuel economy actually improves. The engine is doing having to do less work since the RDX is already moving. I generally punch the trottle/ goose the turbo to get moving and then back off when I get up to speed.

    City driving reduces fuel economy dramatically. In my V6 Accord, I'd generally get 270 miles of city driving out of tank of gas vs 450 miles while on the highway.
  • wwestwwest Posts: 10,706
    Has anyone tried "wiring" the wastegate fully open to determine the FE improvement..??
  • Have you, wwest? You have been posting that same line on every Acura message board for the past 3 years. Why don't you try it and post some results.
  • wwestwwest Posts: 10,706
    Can't really afford to buy an RDX, or the CX-7, just to experiment. But should I decide to purchase then the CX-7 with DFI would be more likely. The DFI aspect would undoubtedly offer the most potential for FE improvment.

    Surprising that the RDX doesn't have DFI, soon to come..??
  • Are you serious that you got 27mpg on the highway?

    Was the TRIP COMPUTER reading or MANUAL calculation based on how much fuel you had to refuel with?

    Hell...on flat highway at 75mph I'd be happy to see it get 24-25mpg!
  • My '07 RDX with ~17000 miles on got 24.5 mpg driving 73 mph with the air running, on a mostly flat surface during a 700 mile round trip 95% highway last summer. Lately it has been averaging 20.9 with 50% city driving. Once summer is over, ethanol % is less, and resume to 30% city the mileage should return to average 22.5. These are all by the car readings, not by hand calculation.
  • On a recent trip to North Myrtle Beach from Frederick Md (450 miles 17.5 gal got 25.7 MPG)

    Yes this was manually calculated and I am positve about the number of gallons.

    Mostly highway (I95) till Wilson NC where backroads takeover.

    This was my driving.

    Around town, which for us is rural Carrol/Howard county, my wife consistently gets 22.5 to 23 MPG. This is also manually calculated.
  • Just came back from 300 mile trip avg 24.5mpg per computer with mostly highway 75mph w/AC - 2 adults. Normal in-town driving is 20mpg.
  • wwestwwest Posts: 10,706
    Drop the turbo and adapt the engine to DFI, 12:1 compression ratio, and the hwy FE would probably rise to ~30 MPG.

    Or even use Toyota's new HSD extended VVT-i technique to transition the engine from "Otto" mode into Miller cycle mode as the throttle opening rises. With the addition of DFI that would allow a 15:1 compression ratio for low engine loading, cruising, and transition to 10:1 to accumodate rising turbo boost with increasing throtte openings, acceleration or high enegine loads/loading.

    35 MPG and 300HP.
  • wwest,

    What's wrong with you?
    This isn't an 'engineer your own engine thread'
    Or a 'WIRE your wastegate open forum'

    Maybe you should spend some more time at your local community college, where
    your ideas can be exploited.
    Instead of suggesting people self destroy their $40,000 luxury vehicles!

    Good luck to you wwest!
    Stay away from open microwave ovens...
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