Speaking of My Darling, she drove the RDX a fair amount during our move of the last three/four weeks...leaving the vehicle running while she was unloading(WAY over 100 degrees here in early August!). I considered this when I saw the average MPG readout of 16.3 !!!

I figured some of my smooth highway cruising would even things out, especially since 'her' average must have been calculated over just a few miles with plenty of 'standing/running'. NO, the readout has not budged in over 4 days of mixed driving. I didn't note the odo reading at the last fill-up, so I have no idea what the actual mileage should read...but I'm pretty bloody sure it's NOT 16.3 with 50% highway miles over the last few days. I've got over 1000 miles before the next service; but I might need to get this checked in the next week. I'm going to try the old school MPG calculation after today's fill-up. Strange...very strange.

 

I just went over 6k miles and my last tank avg 29.2mpg which was about 80% expressway driving and 20% light suburban. This tank(light just came on today) is at 28.3mpg. This tank is about 70 light suburban and 30% expressway. Anyway, my point is, prior to these last two tanks I've pretty much avg 24.5 and that is what my overall mpg from inception is. However, these last two tanks have raised the overall mpg by .1 per tank so now it is 24.7mpg since inception. I've never really bought into the theory that an engine suddenly gets a lot better mpg after 5k miles or so mainly because I have never really noticed it before. But these last two tanks have been much higher than I anticipated. My driving conditions don't vary all that much. I'm pleased at this development and almost wondering if it's to good to be true. I'm right at 400 miles on this tank and it will probably take no more than 14 gals so my gas computer on the car appears to be pretty exact. If this keeps up it would be outstanding. I think my lowest tank was about 21mpg during the early winter last year.

 

Dang, I'd love to get 30+mpg...

I don't drive my RDX too much, occasionally I will commute to work (<5 miles one way) but some days I don't drive it at all. It's still fairly new, and other than the trip back up to Seattle (bought the car in Portland, OR), it's gone probably less than 75 miles on the freeway.

Just took my first long road trip from Seattle, WA -> Spokane, WA -> Coeur D'Alene, ID. 15 miles of city driving on the tank before the drive out. I got 333 miles before the light came on, about ~24mpg. Almost entirely 70-80mph the entire trip w/AC on, 4 passengers and a full (but light) load in the back.

The tank back got 350 miles before the light, so just pushed me over 25mpg. This time was driving 60-70mph the entire trip.

This was a little surprising to me, I thought I'd hit 28+mpg easy. But then again, I did have almost a full car of passengers and luggage.

My previous car was a 2009 Subaru Impreza 2.5i sedan stick shift (NOT a turbo WRX) and it really didn't do much better. With just my usual city driving, got under 20mpg and at my best, driving solo on the freeway, got close to 28-30mpg. I'll take having a bigger, more powerful, taller, roomier RDX over the Impreza any day. I do wish the RDX had a bigger tank, surprised to see it at only 16. My Impreza was nearly a full gallon bigger in a 2.5liter 4-banger.

 

I forgot to mention that the last two tanks I posted about above was 80% solo with virtually nothing in the trunk.

 

For those anxiously awaiting my update, I've been driving the C70 and haven't filled the RDX yet. Stay tuned!

 

I recently got a 2014 AWD RDX I currently have about 500 miles o it and my MPG meter has been hovering around 16. 90% of my driving has not been on highways but the car is advertised as 19 city/27 highway so I am still well below where I should be. When I drive, I constantly keep my eye on the mpg meter and am very cognizant of my driving habits. I try not to accelerate to quickly and do a good amount of coasting, especially into red lights and stop signs. It's not fun driving this way and I am getting crappy MPG so it's all for nothing.

Could there be something wrong with the car?

 

Yeah, you only have 500 miles on it. That's only like 2 tanks of gas total give it more time. Usually they get better mileage as you break the engine and seals in. Also maybe it's hilly in your area, that will affect mileage too as well as sitting in traffic.

 

I have almost 5k and 4 months on the 2013 FWD RDX and like most I get 18mpg during city driving with mild acceleration on flat roads with normal stop light activity. If there's heavy traffic it would probably be more like 15 mpg.

For the highway, stay at 70mph or below and the car can acheive 31+ mpg if driven at least 15 miles without traffic. Take it to 75 mph and I doubt you'll see the rated 28mpg.

 

Drove from Austin to Houston on Friday afternoon.
spouse, 2 kiddos and stuff piled high that it blocked my rear view mirror.
Filled up with 87oct right before leaving via Hwy290 and arrived in Houston with 30.7mpg on the iMID. I averaged 65-70 mph with about 6,000miles on the odo, ambient temp was 97deg, quite humid and negligible wind.

 

With almost 4K and a lot of city driving, I get 23.5 mpg city and 32 highway in a 2014 RDX AWD. We have a lot of hills and bridges in Pittsburgh. I thought I would see around 18-19 city and only 28-29 highway. Closer to 3K is when I noticed a change in the mpg. I have been running Exxon Supreme 93 octane.

For those concerned with the fuel mpg, allow the engine to break in. You will see a difference soon enough.

 

What is amazing is that the new MDX with the Earth Dreams engine is getting better MPG than the smaller RDX. I wonder when the RDX will get the ED engine? Now that would be a nice package.

 

Went to Greenville and back (80 miles one way) and averaged 30.5 @ 72mph. Hilly terrain, 93 oct with 5200 miles on the odometer. Last time I did this trip is was on 87oct and hit 29mpg @ 64mph average.

 

EPA on the 2wd models is exactly the same. On the 4wd versions the RDX get's one better city and the same hwy. So the MDX is NOT getting better MPG. The MDX weighs a lot more and the direct injection helps it get about the same mpg as the RDX. I agree that the DI engine would up the MPG in the RDX to an even better place. However, I'm just a little leery on the long term stability of the these direct injected engines especially since I plan on keeping my RDX for the long term! Time will tell. Hopefully, by the time I need to replace my RDX the DI engines will have had time to work out any bugs if necessary.

 

The only long term issue I've seen thus far with direct injection engines is carbon buildup on the intake path. Without direct injection, you have the fuel spray to clean this off, but you don't have that with direct injection. I don't know of anything else really that affects reliability. While it isn't as broadly used, it has still been around for a while, though only really became popular recently with the MPG race and trying to lower emissions.

 

"While it isn't as broadly used,"

If it's been around, why hasn't it been used more? Is it more expensive to build or is it hard to get right? Seems like if it was just as cheap to build and reliable they would have starting using it sooner and more. I'm not that knowledgeable on the technology but I do wonder why, if something seems great on the surface, it isn't in widespread use already.

 

It's more expensive. You need a high pressure fuel system. The reason it wasn't widely used in the past is mainly due to the cost difference and demand as far as I know. There was no real need for it before. You wanted more power, you added displacement and cylinders. In general, people didn't care that much about fuel economy or the environment. Now, everyone is very conscious of both. Primary concern tends to be fuel economy, and the better that is, the more environmentally friendly it is.

 

Makes sense. Just hope the high pressure fuel systems hold up and the carbon build up doesn't lead to expensive maint. down the road. One expensive repair bill can negate a lot of gas savings.

 

I had a recent discovery with my 2013 RDX (11K miles on it); non-ethanol gasoline makes a dramatic difference, compared to more common fuel which contains up to 10% ethanol (it says so on the pump). Try a tank or two of non-ethanol 91 octane fuel.

In my highway driving, it results in a 10-15% mpg improvement. Find stations near you: http://pure-gas.org/index.jsp

Bet you'll go over 30 mpg with it, easy.

good luck,

woody

 

My point was, on a vehicle weighing 200-300 pounds more, it gets the same EPA mileage as the smaller lighter RDX. The feedback from owners of the new MDX seem to show it gets better mileage than RDX owners report. With minimal reports on Fuelly.com it looks like both cars are too close to call. If they put the ED engine in the RDX it would be a nice move.

The reports of carbon build up on some engines are pretty well reported, especially Audi. But Honda appears to have taken some time before they can out with a main stream DI engine on the Accord. The theory is that they were making sure they got it right.

It may help to run synthetic oil and an oil catch can on a DI car.

 

"The feedback from owners of the new MDX seem to show it gets better mileage than RDX owners report. With minimal reports on Fuelly.com it looks like both cars are too close to call."

Haven't seen seen or heard anything "from owners" that it's getting any better than the RDX. Where are you reading or hearing this? I would say "too close to call" is exactly what the EPA numbers suggest.....they are virtually the same with the RDX AWD getting just a tad higher. Still, very good since the MDX is bigger and heavier. If I needed the extra space and wanted to spend another 7 grand or so I would look at the MDX. But for my purposes I like the size and nimbleness of the RDX.

 

https://acurazine.com/forums/3g-mdx-2014-2020-414/real-world-mileage-mdx-2014-a-891219/

 

Just to add my data point, in my first measured tankful (with about 800 miles on the clock) I calculated 25.3 mpg, essentially identical to the display reading of 25.2. This was mostly in-town driving, although not much stop-and-go, and maybe 1/4 highway.

Since the display seems to be very accurate, I'm sure I'll be able to hit >30 on highway trips.

One funny thing - I find myself driving with a lighter foot when the mpg display is staring at me. (I'll need to shut if off for more, er, enthusiastic driving. )

 

For my second tracked tankful, I took a long drive consisting of about 2/3 highway, some two-lane "country" roads and a bit of the city. Returned 28 by the display and 28.3 calculated.

I didn't do an extensive study, but by watching the display, it seems the best mileage I attained (besides going downhill, of course) was on those traffic-free two-lane roads at about 45 mph or cruising on flat sections of freeways below 65.

Gotta say I'm pretty happy with the mileage - and with the fact that the display seems to be very accurate (unlike other vehicles I've had).

YMMV.

 

From my experience with previous cars the RDX MPG calculator has come the closest. For me it's off by about .3-.5 MPG too high vs fill-up calculation. Compared to other cars who were off > 1 MPG this is pretty good.

 

Three fillups for me and very pleased with the mpg gauge accuracy. Not sure if it'll break me of a 30-yr habit of manually calculating! So far, my calcs show me averaging about 25mpg on 75% freeway without traffic at 70mph+. My driving includes some steep hills to get home, plus my tendency toward spirited driving. True, the gauge tones it down somewhat as I compete to better my results.

My '10 Prius routinely differed from the computer by 3% to 6%. I'd think like, yay, 50mpg! Then it would translate closer to 47.

 

I can't imagine how frustrating it is to get only 47mpg

 

99% driving in stop and go traffic so my milage is horrible - about 220 miles for a full tank of gas.

 

The frustrating part was driving the Prius!
And it took every tactic and effort to get my supposed 50.
(coasting, drafting, driving like a granny, etc.)

 

Computer is showing 17.5mpg average after 3k miles or so. My wife drives it locally at least 95% of the time so I am not surprised. She also idle a lot during hot days.

To give some perspective she got 17.x mpg in a V6 Rav4 as well. The average rose to 21.5mpg in the same Rav4 after I started driving it. Although to be fair my drive is at least 50% highway.

 

Pretty much similar results here. I noticed that I hit the 30+ mpg mark on the highway one time but I was going very easy on the right foot to see what I can accomplish. I too use 89 octane gasoline most of the time. I go to 91 when I am pulling a trailer.

 

36mpg, what kind of fuel are you using? 91 octane.

 

Sorry I just noticed you said 91 octane already.

 

Try a tank or two of non-ethanol 91 octane and let us know how the mpg responds.

 

After 2000 km I'm getting equivalent of 19mpg. Premium or regular fuel makes no difference. This is driving it VERY conservatively in mixed highway and other roads (but not heavy traffic). Hoping it gets better soon!

 

Overall mpg since day one for around 4K miles reads 23.5 if the read out is correct. Only use premium, it's worth the extra few bucks/fill up.

 

first off, the machine is not broken in, gas millage will not be near EPA for at least 5K miles

edit: removed 2 and as this was posted in june

 

Not sure how you've been measuring 'worth'; but it's been discussed at length regarding the use of various octanes.

Just for one more approach, we made a 400 mile trip this weekend, 90% interstate with speeds of 75-80mph when traffic allowed; but also some congestion along the way with speeds dropping below 60. About 10% of that was 'local' traffic with a bit of stop and go, access roads, etc. Looks like the overall mileage was 28+mpg on 87 octane fuel. For a true value to value comparison, 'premium' fuel would have to return an additional 3mpg average to make it a wash. As I've mentioned in other threads, at 1500 gallons per year between the two vehicles, I'll take that $600 difference and put it toward a payment or car insurance. In this Acura and a half-dozen Volvos, I've not been able to demonstrate an increase in mpg that corresponds to running higher octane fuel, be it 89 or 103. I will bump up the octane if I'm headed toward our mountain house or running fully loaded(hasn't happened in years), Just my two cents.

 

With premium selling for just 20 cents/gallon more I'll stick with it. I appreciate your insight on the matter, though. Thanks

 

Good point...unfortunately it's pretty much a full 40 cents/gal higher here in central TX. For those penny pinchers who want to run 91 around here, they could blend 89 and 93...at least in theory.

By the bye, for the Costco shoppers among us, Costco is showing a much increased 'potion' of cleaners in their fuel, much more than the minimum required. This may open another door for saving a few bucks on 'premium', since that grade is usually even cheaper relatively, as compared to branded stations around here.

 

Yeah, in Chicago area the spread is about 19 cents per octane upgrade or .38 more for premium versus regular at branded stations. I run midgrade at 89 octane and have averaged over 24.5mpg for 9500 miles. Not bad for heavy suburban Chicago traffic IMO.