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It's the SH-AWD. That system is super parasitic on the fuel economy. It's constantly moving power back and forth and side to side. Willing to bet the Mazda system (even in AWD) is probably RWD most of the time until slip is detected. Acura should have went sport hybrid on all their trims instead of the mechanical SH-AWD. More power, better fuel economy, and better off power handling. Win-win-win.
SH-AWD isn't helping for sure, but Honda/Acura normally aspirated engines with SH-AWD really aren't too bad. The Pilot and base MDX both offer competitive fuel economy, for example. But add a turbocharged engine and the MDX Type S guzzles premium at an alarming rate. As much as I dislike the touchpad, it's really the fuel economy that's keeping me from seriously considering an MDX Type S.
SH-AWD isn't helping for sure, but Honda/Acura normally aspirated engines with SH-AWD really aren't too bad.
The SH-AWD system is mostly to blame. Honda’s 2.0T is actually very good. In a 3,400 lbs Accord Touring, the 2.0T delivers 35 mpg at 75 mph. In my less aerodynamic, 3,750 lbs, FWD RDX, I see 32+ mpg at 75 mph, on regular fuel.
SH-AWD isn't helping for sure, but Honda/Acura normally aspirated engines with SH-AWD really aren't too bad. The Pilot and base MDX both offer competitive fuel economy, for example. But add a turbocharged engine and the MDX Type S guzzles premium at an alarming rate. As much as I dislike the touchpad, it's really the fuel economy that's keeping me from seriously considering an MDX Type S.
Totally fair points as well. I think that Honda went for all put performance and threw fuel economy to the wind...strange considering their whole "earth dreams" line of engines.I get the sense that the MDX Type-S and RDX would both deliver a lot better fuel economy if driven very gingerly (kind of the opposite of the way they're made to be driven though to be honest).
With that said, there's no way around it the RDX and MDX-S deliver really poor fuel economy considering the FWD bones and relatively light curb weights. An X5 40i is rated at 21/25 city/highway whereas the MDX-S is rated at 17/21. This would make sense if the MDX weighed more, but it doesn't. X5 weighes ~4850 pounds and MDX is ~4750 pounds.
Originally Posted by Baldeagle
The SH-AWD system is mostly to blame. Honda’s 2.0T is actually very good. In a 3,400 lbs Accord Touring, the 2.0T delivers 35 mpg at 75 mph. In my less aerodynamic, 3,750 lbs, FWD RDX, I see 32+ mpg at 75 mph, on regular fuel.
I definitely feel that SH-AWD is a significant factor with fuel economy. But if you look at the EPA figures, the RDX FWD is only rated at 1mpg more than SH-AWD. I would expect it to be significantly higher, say 3 MPG+ higher in both city and highway numbers. Not at all discounting your real world experience, I definitely feel like the RDX is capable of at least acceptable fuel economy if driven gingerly but any heavy foot and you will feel it.
The SH-AWD system is mostly to blame. Honda’s 2.0T is actually very good. In a 3,400 lbs Accord Touring, the 2.0T delivers 35 mpg at 75 mph. In my less aerodynamic, 3,750 lbs, FWD RDX, I see 32+ mpg at 75 mph, on regular fuel.
I'd have to get out and push for several miles to achieve that mpg #. What conditions did you get 32+ mpg. 75 miles per hour - AC on, flat terrain and what time of the year (temps and wind)? That seems very unrealistic in normal day to day real world driving.
Best I ever got on my Aspec SHawd was 27.4 mpg, going 72 mph on cruise for 580 miles in mostly flat freeway driving with little or no traffic. Tires at 38 psi, summer temps of 93-96 degrees, ac on 68 temp, light wind, 19k miles on the odometer and a fresh engine air cleaner.
The aero efficiency of the RDX is not great - Drag coefficient = .32 and a 2021 Accord is .28. Compare that to a Tesla Model Y = .23. That will play a HUGE part in mpg or kw efficiency.
The aero efficiency of the RDX is not great - Drag coefficient = .32 and a 2021 Accord is .28. Compare that to a Tesla Model Y = .23. That will play a HUGE part in mpg or kw efficiency.
This is a huge point and not one I considered (but should have)! I was curious what the X3 was at and found the following:
"With a drag coefficient of 0.29 and 0.30 respectively, the BMW X3 and BMW X4 boast the best levels in their segment. The reduction of air resistance not only helps reduce fuel consumption, it also offers benefits in terms of noise comfort. In addition to aerodynamically optimised vehicle proportions, the two models feature an enclosed underbody structure. Further aerodynamic measures include the roof spoiler and the active air flap control."
This is a huge point and not one I considered (but should have)! I was curious what the X3 was at and found the following:
"With a drag coefficient of 0.29 and 0.30 respectively, the BMW X3 and BMW X4 boast the best levels in their segment. The reduction of air resistance not only helps reduce fuel consumption, it also offers benefits in terms of noise comfort. In addition to aerodynamically optimised vehicle proportions, the two models feature an enclosed underbody structure. Further aerodynamic measures include the roof spoiler and the active air flap control."
So the X3 is closer to the Accord rather than the RDX!
X3 is still a semi brick compared to the Model Y Performance. A less aero vehicles will take more power/torque to keep going as speed increases. That physics - ain't no getting around it.
X3 is still a semi brick compared to the Model Y Performance. A less aero vehicles will take more power/torque to keep going as speed increases. That physics - ain't no getting around it.
Higher elevation = Mountains terrain with BIG hills, decreased performance due to thinner air volume and will not be off set by thinner air over the vehicle.
What conditions did you get 32+ mpg. 75 miles per hour - AC on, flat terrain and what time of the year (temps and wind)? That seems very unrealistic in normal day to day real world driving.
Best I ever got on my Aspec SHawd was 27.4 mpg, going 72 mph on cruise for 580 miles in mostly flat freeway driving with little or no traffic. Tires at 38 psi, summer temps of 93-96 degrees, ac on 68 temp, light wind, 19k miles on the odometer and a fresh engine air cleaner.
The aero efficiency of the RDX is not great - Drag coefficient = .32 and a 2021 Accord is .28. Compare that to a Tesla Model Y = .23. That will play a HUGE part in mpg or kw efficiency.
Conditions? Pretty much all the time on flat roads. In winter, with winter-gas and extra dense air due to cold temperatures, it may drop to 30 mpg at 75. But 32 mpg at 75 mph is just what it does. 90% of my RDX’s travel is short tips in “suburban NJ.” For the last 9,245 miles, my FWD RDX has averaged 27.8 mpg, on regular fuel. Without trying, the FWD RDX is reasonably fuel efficient, not that far off the older 2.0T Touring Accord.
I agree that a drag coefficient of .32 is not great by today’s standard. According to this online calculator,
a 4,000 pound vehicle with a frontal surface area of 25.5 square-feet and a drag coefficient of .32 needs 33.4HP to maintain 75 mph. If that same car had a drag coefficient of .29 (BMW X3), it would need 31.8 hp to maintain 75 mph. That is a 1.6 HP difference. That might not sound like much, but 1.6 hp is 5% more power which implies 5% more fuel. That’s the difference between 30.0 mpg at 75 mph 31.5 mpg at 75 mph. At low speeds aerodynamics have much less impact. In either car, it takes 8 hp to maintain 40 mph.
For the purpose of discussion, at higher elevations naturally aspirated cars lose a lot of power and turbocharged cars lose some, depending on how accurately the ECU can compensate for less air with added boost. As you say, maximum performance will be less at higher elevation. However, highway fuel economy will improve. They are two separate things. At higher elevation, the 4000 lbs car with a .32 drag coefficient that required 33.4 hp to maintain 75 mph at sea level may need only 30 hp to maintain 75 mph in the thinner air. That means the engine need only burn enough fuel to produce 30 hp, which will be less than the amount of fuel to produce 33.4 hp. The ECU maintains the same stoichiometric ratio and therefore the engine maintains the same level of efficiency. Higher elevation equals slower maximum acceleration because of less peak power but better highway fuel economy because of less overall drag.
For the last 9,245 miles, my FWD RDX has averaged 27.8 mpg, on regular fuel. Without trying, the FWD RDX is reasonably fuel efficient, not that far off the older 2.0T Touring Accord.
Not as many FWD RDX owners complaining as much as SHAWD ones...
Not as many FWD RDX owners complaining as much as SHAWD ones...
Lol that's because most RDX owners didn't want to pass up on a world class top of the line AWD system with true torque vectoring. As someone who's had a lot of experience with Quattro, 4XMotion, Xdrive, Quadra Drive (II), and many run of the mill slip and grip systems, nothing compares to SH-AWD in cold and icy weather (IME of course). It is a no brainer to get SH-AWD to me.
We just completed a 4700-mile trip from Florida to Colorado and back in our 2020 Advance with SH-AWD.
Most of the trip was interstate at posted 70 MPH, 75 MPH and some 80 MPH posted in Texas and Oklahoma. Texas is interesting because we were on some fairly winding two-lane roads that were posted 75 MPH. Sport+ really worked well on these.
Fill-ups were Regular, 87 octane, except in higher elevation areas where octane ratings are lower. At those fill-ups I used Mid-grade to meet Acura's 87 octane minimum recommendation.
Here are the final numbers:
4741 miles (trip)
187.9 gallons (trip)
25.23 MPG (trip)
17 Fill-ups
28.14 High Fill-up MPG
Overall MPG for the life of the vehicle, 3.2 years, is 22.60 on Regular, 87 octane. This is mostly city driving but includes eight other road trips ranging from 1,700 to 3,400 miles.
Our highest Trip Computer Average MPG on the trip was outstanding! 199.9!
How did we accomplish this? First, you go up to Monarch Pass in Colorado, elevation 11,312 feet. Then you head towards Salida, Colorado, elevation 7,083 feet, and watch the average climb!
I have our Trip A configured to reset at Ignition Off. We parked at the pass, turned the car off and captured the obligatory photo of the sign.
Then we began our descent.
I suspect the actual average was higher than the 199.9 shown in the image. It appears Acura stops at that number and doesn't go any higher. I say this because as we were going down, the average would slowly climb. e.g.,75.5, and when we would occasionally go uphill, the average would quickly start to drop. Once we hit 199.9, it stopped increasing and when we leveled out on our way to Salida, it was quite some time before the average started to drop below the 199.9 value.
Anyway, it was a great trip and I thought you would all appreciate the average MPG we achieved!
Baldeagle (07-11-2023),ELIN (07-10-2023),HotRodW (07-10-2023),khaoohs (07-10-2023),MJ4RDX (07-13-2023),RDX10 (07-10-2023) and 1 others liked this post. (Show less...)
after I tuned my car with Ktuner to stage 2 ( installed catted downpipe PRL before ) my fuel consumption descreased for a few liters\100 km ( I live in Europe ). I am using the high octane fuel
after I tuned my car with Ktuner to stage 2 ( installed catted downpipe PRL before ) my fuel consumption descreased for a few liters\100 km ( I live in Europe ). I am using the high octane fuel
07-06-2023, 11:46 AM
