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Acura RDX Real World MPG



  • wwestwwest Posts: 10,706
    Putting a smallish 4 cyl. in the RDX isn't so much the problem as is the fact that it is turbocharged. A normally aspirated engine would have a compression ratio of 10:1, 12:1 with DFI in the CX-7. In order to "accomodate" the dynamic increase in CR with turbo boost the base engine CR must be derated from the norm.

    Since most of the time you spend driving the RDX you are off-boost you are sacrificing a serious level of FE improvement for the rare and brief periods of "on-boost" acceleration.

    Mill the engine head to raise the CR to the "standard" of 10:1 and "wire" the turbo wastegate fully open and you will likely see an FE improvement in the range of 30-50%

    Or even better use VVT-i to dynamically change the CR from Atkinson cycle mode for cruising but into the Miller cycle as boost rises.

    So much for TURBOCHARGING...!!
  • then coast from there?
    The traditional ease the pedal acceleration won't save gas?
  • mark4490mark4490 Posts: 16
    I've finished my first tank of mystery gas (dealer supplied). Some city driving (steep SF hills), lots of highway miles, and I went up and down the Santa Cruz mountains five times.

    330.7 miles/14.966 gallons = 22.1 miles/gallon

    Love the boost when you need to merge and pass. The handling is phenomenal on the twisty mountain climbs and descents! I admit that I went pretty easy on the gas pedal as the engine is still breaking in, but I still has numerous full-on accelerations to merge and pass on the freeways. Gas mileage was probably improved as descending from the mountains was most engine braking and little to no throttle.

    The only negative so far is that the navi got lost in the heavy tree cover of the SF mountains.
  • mark4490mark4490 Posts: 16
    I got back from a trip north to the coast. From the South Bay, N101 to Fortuna and back along the Pacific Coast Hwy (CA-1).

    720 miles/35.196 gallons = ~20.5mpg

    Not bad considering we were rolling through high elevations so the boost was kicking in even while descending.

    The drive down CA-1 was a BLAST! I finally got to really test the SH-AWD. I'm not sure, but I think the VSC kicked in on one corner that I overcooked. It was both downright terrifying and thrilling at the same time. There was no way I was going to take my eyes off the road and glance down to check how many bars I was up to, but on one sweeping corner I saw the meter go up to 3 bars.

    We also had a huge scare and almost ran out of gas on N101. The low fuel indicator had gone off, but I thought I could go another 50 miles before it got serious and we'd have to look for a gas station. The low fuel light had gone off on me before. That time I went 40 miles and found out that I still had 4+ gallons left in the tank when I filled up. Luckily, my GF is from the area so she knew that there was a 24 hr gas station near Garberville. When we filled up I was surprised that we put in 17.3 gallons! I thought we'd have ~3 gallons left! I'm not sure if we would have made it to Garberville. We'll fill up when it gets down to 1/4 tank next time.

    This brings up an issue I have with the navi system. Little towns with little to no services show up (Leggett, Piercy), but bigger towns with (ie., Cloverdale) don't unless you zoom all the way in. I don't think that gas station showed up on the RDX navi system, either. My Garmin handheld GPS is much better and more reliable. If I didn't have a "local" with me I could have been in serious trouble.
  • geohovgeohov Posts: 23
    I'm wondering why everyone gets such poor mileage? On my 2010 RDX I'm on my second tank of gas. I'm getting 22-23 mpg driving around the northern suburbs of Chicago. This includes about 40% highway at which I drive 70-80 mph. I don't gun it from a stoplight. I find that it still moves out ahead of the cars around me without having the turbo kicking in. It has awesome power when you ask for it. I'm as happy as can b with my RDX! :)
  • wwestwwest Posts: 10,706
    "..I'm wondering.."


    Most of the time the RDX runs in detuned/"derated" mode. During "cruise" mode the compression ratio is significantly reduced from the Otto mode standard.
  • I'm getting slighly better than EPA.

    I am "breaking" her in, about 500 miles, and drive 10% city, 90% highway, averaging about 22.5-23.5 on the trip computer.

    Average speed is 69 mph acc to computer.

    I floor it here and there, but largely feather, stay out of boost, and my range is close to 350 miles to a tank so far. . .I should hit 400. . .will keep everyone posted. . .the new DFI def should improve mileage. . .

    Remember EPA revised all mileage estimates in 2009 because of the "cash for clunker" program, so estimates are off in FAVOR of more mpg apparently now. . .
  • So far with about an average speed of 50 mph, I'm getting anywhere between 21-22mpg with my SNOW tires on, Bridgestone DM-V1's (235/55/18's). . .

    oddly enough, I'm getting the same mileage as my 2005 Evolution VIII which was 800lbs lighter. . .go figure, technology. . .
  • wethertonwetherton Posts: 6
    2nd tank of gas, not dealer gas at time of pickup got me 22.4 with city driving but we live on the ouskirts, most driving is city highways, not a ton of stop and go. Normal to light driving. Pretty happy with that MPG. Secondly, for the MPG nerds, I found a great iphone app "gas cubby" it is free if you can handle the pop ups, very nice app
  • lildukelilduke Posts: 16
    I have the 2011 with SH AWD.

    First tank averaged 24-25.9 MPG in stop and go construction traffic on the highyway.

    Second was about 23

    Third has a little more around town driving and was about 21

    and now on my 4th I am at 19.5.

    On the highway, I'm pretty much 70mpg or lower 15 miles each way then local roads with stop and go for the other 5-6.

    I try not to step on it and use the turbo as much on local roads, but occasionally I do have to use it. Same on the highway. I'm at about 800 or so miles so the engine is not totally broken in.

    Shouldn't the average MPG go up as the car gets broken in? I'm not looking for 28mpg but 21-22 would be nice.

    2014 Accord Touring

  • lildukelilduke Posts: 16
    Oh, My first two tanks were Shell and BP gas, last two were Costco and Marathon. Since it uses premium, should I be sticking with Shell, Mobil and BP or is it OK to go with the others like Citgo, Speedway and Marathon?

    2014 Accord Touring

  • wwestwwest Posts: 10,706
    edited November 2010
    On the highway, simply cruising along, or anytime the lockup clutch is engaged, your RDX engine is running in detuned/derated "mode". An optimal base/native compression ratio for a N/A DFI (DISI) engine should be ~12:1. But your engine is forced induction so the non-boost, base/native compression ratio must be substantually lowered from what would otherwise be considered optimal for a DFI engine.

    10:1 with certainty and maybe even as low as 7-8:1 if the turbo is to spin up really quickly and substantually raise the effective CR. So you can expect hwy FE about 20% lower than an equivalent displacement volume DFI engine.
  • Hey, just wanted to share our numbers. Just purchased this used with 40k and on the first tank we have gotten 24-25mpg mostly highway 65-75mph. My fiance drives to school which is mostly small highway and got 25.5mpg with a few stops to get on different roads. Average speed for her is probably 50mph the whole 80 mile trip. I think these are very good numbers and we mostly do not hit traffic which may be the reason but we also don't stomp on the gas too much either. If you are getting less than 20 mpg in normal driving you either have a lead foot or highly unlikely have a vehicle defect. Good luck!
  • m6userm6user Posts: 2,952
    Anybody have any info on the real world 2013 RDX MPG???
  • radoncgsradoncgs Posts: 58
    I am also interested in knowing the real world MPG, comparing with x3, q5 then decide which one to buy.
  • My RDX is about 6 weeks old. It's too early to say. Mileage has been all over the map (along with my driving situation, very mixed and inconsistent), however one thing that's starting to piss me off is I suspect the mileage meter on the dash is consistently inflated. My most recent tank showed 24.4 MPG, but the actual mileage was 22 MPG. I'm going to watch more closely the next few tanks.
  • rickpoolerickpoole Posts: 27
    That's exactly what I've seen on my 2007 TL and my 2010 HS250h - they both read 2-3 MPG higher than manually computed. Even averaging it over 3-4 tanks it still shows 2-3 MPG higher. Almost everyone I've talked to who correctly computes their actual mileage says their MPG meter reads ~10% higher than the actual mileage.
  • radoncgsradoncgs Posts: 58
    thanks for the message. Please update when you have more information.
  • I seem to settling consistently in the 24-25 MPG range, that's with a mostly highway commute plus about a 1/2 hour of city traffic every day. I think that's pretty good.
  • m6userm6user Posts: 2,952
    Tks. Is yours AWD or FWD?
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