Revised Gov MPG 17-22
 

The revised US Gov EPA gas mileage estimates are out and our RDX goes from 19-23 down to 17-22.

See this for more info:

http://www.fueleconomy.gov/feg/calcu...odel=RDX%204WD

yep. this year marks the epa's new measure in MPG's in vehicles sold here. 17/22 sounds a lot more realistic than 19/23.

Very dissappointing!

Not really. Virtually all cars/trucks will drop a few MPG with the new rating system. Its all relative.

It is what it is. I already have an RDX, so whatever! I love my car!

Seems more realistic to me...all of the new ones do.

I don't see the big deal. You get what you get with any vehicle. It went down pretty much the same margin for each one I checked on that site, new vs old ratings.

On higher rated epa ratings old vs new they went down even more overall.

I know one thing I get as good or better than the old epa ratings myself.

Drive smart as we all should and the gas mileage will come accordingly.

At least my last 3 cars/trucks were closer to the MPG rating than my RDX. However, the new rating is exactly what I get now for the RDX.

I got better than EPA for my previous car - driving very aggressively. I get worse than even the new EPA ratings with the RDX, even driving fairly sedately (as in other cars get annoyed with me).

The new MDX ratings are 15/20 - ouch!

I have to admit, I do find the variation in MPG experiences interesting. They seem to go far beyond driving style and city vs highway. I'm really starting to wonder if there's something more to it with the RDX. I have yet to get below 19 on a tankful, and seem to be averaging around 20.5. However, I HAVE noticed I get worse mileage the colder it gets outside - same drive to work every day, same gas station. I just can't help but wonder if the turbo, intercooler, etc. interaction means the firmware still has some bugs...

Mike

Now that all the other vehicles/SUV/crossovers have a lower rating, the RDX numbers suddenly don't look so bad anymore!!!!!!!!!!

Yep, me too. Seems like the new numbers are more realistic.

Check out an F-150: 13/17

And here are some numbers of,

CX-7 AWD: 16/22

Murano: 17/23

Outlander (2007 model with 220hp): 17/23

X3 (new engine): 17/24

Jeep Liberty: 15/20

Tribeca B9: 16/21

Looks like some manufacturers *cough*Toyota*cough* had more inflated mpg figures than others. Honda's and Acura's line-ups were affected about the same across the board.

But looking at those numbers, the RDX is still solidly competitive in its class against its direct competitors.

Has something changed in recent years, it seems like the cars I used to buy would get their EPA numbers easily, but the last time I bought a car was 7 years ago. I do remember a change maybe 15-20 years ago that dropped all the ratings and since that point on the cars I got seemed to match their EPA ratings fairly well (until this RDX).

So, either the ratings changed since then (and they are changing them back?) or maybe the manufacturers learned how to game the old system and so they had to change the methodology to throw a wrench into their gaming...?

FWIW, my RDX is having trouble even matching the new ratings.

I do remember a corvette that had a key-switch in the center console that would switch it from performance to economy mode and it turned in some amazing EPA numbers in the economy mode - the reviews said at the time that the engine management transformed itself to match the expectations of the EPA tests in the other mode. Allegedly this mode was so that your 16 year old kid with the brand new license and the valets couldn't go out hot-rodding in your new sports car...

One recent generation of the Vette had a skip shift feature in the manual trans where it would gate a 1-4 shift instead of a 1-2 shift, in the interest of fuel economy. Seemed kind of retarded to me. I'd rather just drive gently and go through all the gears.

so everytime i fill up i reset my "trip A". right after this fill up i hit the freeway and :thumbsup:

http://side808.smugmug.com/photos/131918715-L.jpg

Damn 34 mpg? How can you hit that?
the absolute best I have been able to manage at highway speeds is abou 22 mpg, my usuall tank of gas has only been about 16-17 mpg w/ over 50% being highway cruising!

haha i just drove six miles. also most of it was down hill haha. i was just amazed because i dont see that high of a MPG on my MID lol. just had to take a pic.

Since the city fuel economy number is subject to countless variables, not the least of which is driving style, the only useful info is steady state level road cruising ie., the highway number.

Interestingly enough, Consumer Reports does their own fuel economy testing and they are publishing 25 mpg highway for the RDX. They are listing it as one of their top 10 fuel efficient "mid-size" SUVs.

It would be enlightening to know at what cruising speed CR records that 25.

I have been getting 23 to 24 highway in ours at 65 in rolling terrain.

My C-5 Corvette (with the much un-loved 1-4 skipshift) is EPA listed at 30 highway and I routinely get 33 to 34.

Bear in mind that EPA figures are based on a class of vehicle, and in smaller print on the window sticker they publish a range that brackets the target figure.

Maybe I drive the 'Vette like a Prius but I can easily see highway economy in the high end of that range.

The Prius fleet, on the other hand, has infamously been running at the low end of the expected range, angering Prius owners. (Maybe they've grown somewhat impatient and are flat-footing the "throttle/electron gate" these days.

That's the thing that strikes me as being odd about the RDX, but there are some people who don't have an issue with the MPG because they are getting match or better than the MPG rating. For the people who are not get close to rating, people automatically assume you must be flooring it or putting low octane gas.

As for me, I'm not an aggressive driver and on my other cars (96' Rodeo and 02' S2000) I get match or better that the MPG rating. It may be the cold weather here in Chicago, who knows for sure.

Moreover, I think Acura logic for using a 4 Cyl turbo is not justifiable considering the new MPG rating. They might as well just throw in a 6 cyl, but that may be a dream. :wish:

May be the 4 cyl helps the weight disturbution of the car??

I wonder how much the dealer installed accesories impact fuel economy? How much does having a "dirty" car with roof rack, additional door molding, spoilers, running boards, etc. impact your fuel economy, relative to a stock RDX with nothing bolted on the outside?

For those of you routinely getting better than EPA mileage, do you have anything extra bolted on?

Likewise, for those who are unhappy with you mileage, did you customize your RDX by adding anything to the exterior?

I suspect if people start to track this we'll see a trend at least as pronounced as the impact of driving style.

It sure does!

When a car turns it rotates about it's center of gravity (CG).
Weight distributed farther from the CG results in a higher polar moment of inertia.
This resists changing direction.

Low polar moment of inertia (weight distributed close to the CG) enables rapid directional changes.

Look at the front/rear weight distribution for responsive cars such as the Mazda RX-8 (50/50) and Honda S2000 (49/51) or Nissan 350Z (53/47).

Compare that to a Chevy Equinox (56/44). The front weight bias results in understeer and low fun factor.

Now consider an RDX that weighs 3982 lbs with a distribution of 52/48. This is in sports car territory as shown above.

The actual distribution is 2071 lbs front and 1911 lbs rear. Let's throw in a V-6 that adds 200 lbs to the front. Now our 4182 lb RDX has 2271 lbs front and 1911 lbs rear for a distribution of 54/46. If the V-6 adds 250 lbs it's even worse at 55/45.

Look at how favorably the RDX compares to it's V-6 competition:

RDX 2.3 I-4: 52/48
Mitsu Outlander 3.0 V-6: 58/42
Nissan Murano 3.5 V-6: 59/41

It's no surprise that the V-6 SUVs are plagued with understeer and slow in transitions.

BMW however, manages 50/50 with their I-6 in the X-3 3.0 and it shows. The X-3 is Acura's target and they hit it rather nicely.

good info, thanks....and the new TL mpg matches what my mom's 07 TL is getting, def more realistic MPG ratings.

I found my TSX to be right on with the original MPG and same with new Accord v-6….

Worried about MPG? Lowering speed is easiest way to improve MPG…aerodynamic drag is a geometric progression….i.e. 65 to 75 creates a heck of a lot more drag than 55 to 65…..staying out of red line helps also....Fun VS $$s…..

well, that sounds about right. after 4500 miles, i consistently get 22.5 to 23.0 miles on the highway & 17.0 to 17.5 off! not much difference & doesn't matter to me because the RDX is still too much fun!!

Thanks for the info 737 Jock! Looking at those numbers, the weight disturbution of the RDX is much better than other cars in this segment except for the X3!

Anyways, isn't the polar moment of inertia has to do with the position of the engine also? Not just the engine weight? So that's why a mid-engined car usually handles better than a front-engined car, or why many FR sports cars now put their engines behind the front axle.

A minor correction here: it seems the 52/48 statistic is a leftover error from the pre-production days of the RDX. A quick check in the official RDX brochure betrays its real weight distribution - a less impressive 57/43.

Correct on all counts!

A "moment" is the weight times the distance from the CG. So a heavier iron block engine placed behind the front axle can have the same moment as a lighter aluminum block placed over or ahead of the axle.

The general idea is to keep the moment as low as possible and equal at both ends to provide "neutral" handling. That is, no tendancy toward understeer or oversteer.

A front weight biased vehicle like a GTI VR6 with an iron block ahead of the front struts will understeer due to the large front polar moment. A Porsche 911 with the engine hanging behind the rear axle conversely has a large rear polar moment and an infamous tendancy to oversteer in the hands of an inexperienced driver. (Both great cars by the way).

Good suspension tuning can minimize the effect, but nothing can change the tendancy of the heavier end of a car to want to rotate around the CG.

Well you are right. I've found that in at least one Honda source and a few unofficial places. Makes one wonder how the initial and later numbers could be so far apart if the latter is correct.

It would appear then that the suspension tuning plus the oversteering affect of the SH-AWD accounts for it's toss-ability.

For what it's worth here is a current Acura source quoting 52/48:


http://www.southviewacura.com/specs.asp?ModelID=12

Well, again the RDX brochure quotes 57/43. Road and Track confirms this, as well. (warning: link is a pdf)

http://www.roadandtrack.com/assets/d...data_panel.pdf

Mpg
 

I notice RDX has almost the same MPG (if not better) as its same size competitors (including Lexus RX350 which is supposed to be the best gas economy in class).

So, I don't understand why most complaints I heard about the RDX is gas mileage. Maybe people are comparing it to the CR-V gas economy (if they used to own CR-V) :2cents: Actually, if most of your driving are local, the difference is very small even comparing to CRV.

I only wish if it takes regular gas instead premium (when we talk about gas money savings) :wish: Gas price is going up to $1.00 per liter this week !!! Actually, for premium gas, we are paying over $1.00 per litres in Canada !!! :whyme:

For the folks in US to get a sense on how much it is in gallons

1 US gallons = 3.7851 litres, and our premium is in general 11 cents more than regular. So, you could be paying a quarter more only per gallons for premium gas, we are paying 42 cents more per gallons :annoyed:

Are you comparing EPA estimates for RDX and its competitors or actual owner reports?

Most of us, or at least in my case, are not complaining about the EPA numbers for the RDX, but for the fact that we can't even come close to them (not even in the same ballpark for city mileage) even with relatively moderate driving. That contrasts to every other car I've owned where the EPA estimates were reliable, even with a more aggressive driving style and even living in a big city with heavy traffic.

The new EPA numbers don't close the gap much on city, though the new highway mileage is close to what I get on a flat highway with sedate driving. If I up the speed a little then even the highway mileage tanks in a way that none of my other cars did (for comparison, when I got my Audi S4 I was younger and wilder and started driving around at 90+ on some of the rural highways until I got too many tickets - the car delivered very close to its EPA rating even at those speeds - yet my RDX loses 10% or more just trying to keep up with traffic in the Bay Area...)

Mpg
 

My average gas mileage shown on the dash (converted from L/100 KMs) is 19 MPG and I have over 11,000 Kms on it. 90%+ City driving.

I totally agree. That's what I have been say about the RDX for awhile. I'm in the same boat; my older cars are at least at EPA rating, my RDX is about 2MPG off and that's is driving even more passive than my other cars.

Not to mention the great steering response with low polar moment of inertia too!

(Edit - scratched my question about which type of gallon - I see you were discussing liters vs. US gallons above already...)

Also, my mileage as shown on the dash is at least 1MPG higher than the real MPG - usually more.

And there are reports on both sides of the coin that I've seen here - some drive aggressively and get decent mileage - others drive sedately and get bad mileage (or drive aggressively and get even worse mileage). It makes me wonder if there isn't a bug in the engine management that has given the cars 2 different personalities... :(