My family just got back from a road trip from the Chicago area to Myrtle Beach, all in all totaling about 2300 miles for the whole trip. The trip was great. We had previously done this trip in a 2013 BMW 5 Series, 2018 Subaru Outback 3.6 H6, and now the RDX. Most comparisons made will mostly reference the Outback as it is the other utility vehicle and the only other one that had any driver assist features, and the other car that was considered for use on this trip again.

Overall, the RDX handled the trip well with 4 adults and a weeks’ worth of luggage. The under-floor storage was helpful in taking care of any smaller bags/loose items. It under -floor area was infinitely more usable than what the Outback has for under-floor storage. Some things were a tighter fit in the main cargo area, particularly the one really large piece of luggage my parents packed in. The taller cargo area of the RDX helped with placing all the luggage, however, I think the Outback had the advantage here as it does have a longer cargo floor in the back as well as more room between the wheel wells. There was plenty of passenger space in the RDX and no one was crammed in, however the Outback had more. I do find the seats and my driving position in the RDX more comfortable than the 2018 Outback. I was not fidgeting in my seat like I had before in my Subarus. I have heard the seats in the latest generation Outback are more comfortable than before, and I did test drive one, but it was not enough time to really get a feel for the seats.

The RDX handled the highway drive quite well, as did the Outback. The RDX has a firmer ride than the Outback, but it was never harsh which was a concern on mine being the car was fully laden with people and cargo. The Outback remained supremely smooth and comfortable even fully loaded but required more steering correction. Both cabins remained relatively quiet though the Outback had a more wind noise come in around the moonroof. The biggest difference was in the driver assist features. Adaptive cruise control was used extensively during the trip. The Acurawatch adaptive cruise generally worked well, however it lacked some of the polish found in Subaru’s Eyesight. Eyesight had a better detection range and coped better with lane intruders at a closer distance. Additionally, when signaling to pass, Eyesight gives some acceleration to help the merge into the passing lane as well. When driving into curves using cruise, Eyesight will reduce your speed a little to help maintain comfort. When approaching slower moving traffic, Eyesight reduced speed more gradually with coasting/light braking whereas I felt the RDX would run up at full speed then stab the brakes at the last second to slow down and maintain the gap. This behavior also extends to stop and go traffic. On the hillier sections of the drive, Eyesight was better at controlling speed, especially on the downhill sections. The BMW did the same despite it not having adaptive cruise control. What the RDX has that the Outback doesn’t is lane centering which I thought worked great. The new Outbacks do have lane centering and I had a chance to give it a good test on the test drive, but the RDX did it better. The Outback does have lane departure prevention which does a great job at trying to prevent a lane departure. During the curvier sections of the drive on I-40 between Knoxville TN and Asheville NC, the RDX felt more at home. The Outback did fine during that section too, but it was not as comfortable in those curves at speed. There were no issues with the powertrains in either vehicle. Their different characteristics afforded them different advantages. The torque of the turbo in the RDX made it so it did not have to rev as high when climbing hills, but the H6/CVT combo in the Subaru remained smooth and quiet even when needing more revs for hill climbing. The Subaru had the advantage in fuel economy too with effortless 400-450 miles between fill ups with the 18.5 gallon fuel tank. The RDX tank is smaller at 17.1, but overall economy was still a bit disappointing with barely getting 300 miles on a tank. I was hoping for a little better on the highway. There were no regrets in taking the RDX on the trip vs the Outback. It really would be a toss up between the two going on the trip next time as I feel either one is a good choice.

 

subiefanILL83,

Glad you had a great road trip. Thanks for sharing.

 

Did you hit the Giant Crab while you were there? We love that place.

 

You took pretty much the exact same trip we just did, except we were in a '21 Ford Ranger. We left the Chicago area on 4/30, stopped in McCormick, SC then went straight for the coast. Drove from Savanah, GA across to Myrtle Beach, SC. Returned Saturday 5/7 and totaled a little over 2,300mi. It looks like we were there at the right time, as their weather has tanked this week. I can assume you got better fuel economy than we did. We averaged about 21mpg, with the best tank being 24.

 

Great write up/review. What was your average MPG for the trip?

Your RDX MPG is similar to mine on a long 1,100+ mile road trip, but with only me in the RDX. My worst tank was 22.6 mpg (head wind of 15-20mph, doing 70ish on cruise and temps in the 50') and best tank was 25.4 mpg (super strong tail wind - 20-25mph, 70mph on cruise and temps in the mid 50's). That was on premium gas, with tires inflated to 37psi.

Your Subaru sips the fuel compared to the RDX.

 

I didn't do any hand calculations, however the trip computer read 22.8 average during the course of the trip. I had reset one of them when we left. I do find the comment about the Subaru sipping fuel a little funny. All my Subaru's were gasoholics in city style driving, but they did sip it on the highway. I had a 2011 Legacy with their 2.5 We drove down to Hilton Head, and averaging around 75-80 mph, I got a tank high of just under 33 mpg, hand calculated on that tank. I believe the epa rating for the 2.5 that year was 31.

 

I know most SH-AWD owners get MUCH less fuel economy than what Acura claims. Given the large number of complaints on this forum alone, I believe Acura could probably be held liable for false advertising. But hopefully without seeming insensitive to the SH-AWD owners' pain, may I state this seems to only apply to the SH-AWD models? My FWD RDX Tech is very similar to the FWD Accord Touring, just with an extra 300 pounds of weight and more aerodynamic drag. My RDX returns over 30 mpg on the highway at 75 mph, not that much less than the Touring Accord. My average fuel economy of mostly “traffic-light laden, NJ suburban” driving for that last 9,000 miles is 27.4 mpg.

 

Impressive MPG you get - wish mine got even close to that. I would have to get out and push for a few miles to get those numbers.

Probably pretty accurate assessment. The extra weight and always on SHAWD takes a lot more energy and is a MPG killer. Also noted wind and a rolling terrain eats up more MPG too.

 

I just completed a 12-day, 1600 mile round trip Baltimore-Montreal-Quebec City with two people and luggage in my 2020 Advance SH-AWD, and got 25-26 mpg per the trip computer. 75mph almost all the way, with 89 octane gas. I regularly get 23-25 in combined city-highway fillups; I’ve now got 21k miles on it over 21 months. Since the gas tank is NEVER empty when the trip computer says it is, actual mileage is likely higher by at least a couple of mpg, although I don’t hand calculate it. I never see 30mpg though.

 

Want 30 mpg? Drive 62 mph.

When people compare the RDX to their old cars (like the Legacy 2.5 mentioned above) it's like they forget about the extra 600 pounds ... The RDX is not bad for what it is, a 4100-ish pound forced-induction, direct injected crossover with a performance oriented AWD system.

The problem is that it's designed to be driven in a fun manner, and you have to stay off boost to get good mileage. I've discussed this way too many times here but everyone ripping on it for terrible mileage is usually comparing it to a naturally aspirated or port injected car, not realizing things like the effect of being "on boost" or the effect that driving a DI engine that isn't fully warmed up has on mileage. Your RDX is capable of matching the city numbers and slightly beating the highway numbers in ideal conditions IF you take some time to understand the various factors that cause terrible mileage. Of course, that's not great, because an older, port injected, naturally aspirated, lighter vehicle will easily get better mileage with no effort.

 

I've noticed this too. When I chose the RDX, I knew i was sacrificing MPG for "fun" (I factored it into the cost of the car). So when I joined this forum I was surprised to see how many people complain about MPG....and also post about their 0-60 speeds

 

I no longer own my 19 RDX, but while I really liked the car, it wasn't good fit for me. I could care less about 0-60 times, and I always seem to have an unusual desire to achieve 30 mpg!!! LOL And, while I got used to it, it was a bit noisier than I would have preferred, and I did not care for the fake engine sounds. BEST audio system (Advance) and BEST seats. I thought the 10 speed trans was very good.

 

Good post and I totally agree. 2,3,4,5, less mpg than what you expected. Big deal! It's an excellent bang for the $$ crossover.

 

On point, JB.

I think I do 0-60 in about 45 seconds and...... I'm actually OK with it.

I'm semi-retired. What's the rush?

 

Good post...and full of facts.

I get it. Many opinions and complaints about gas mileage in our RDX, but after almost two years of driving my 2020 Advance (using 92 octane) over 25,000 miles in every type of weather, using all four driving modes when needed, every sort of freeway, mountain, city (Seattle!) hills at the end of the day as I look at my MPG gauge today it reads 28.2. I'm good with that. I'm doing 0-60 in 45 seconds so I'm not using the paddles or racing that Subie WRX next to me at the stop light. It's decent mileage for what we have, driving modestly and enjoying the experience. What else can I ask for?

 

I agree with your comments that driving behavior (boost) plays a very large part in fuel economy. But can you please explain why you stated port injection provides better fuel economy that direct injection?

 

So, DI definitely provides better mileage overall, but when a DI engine is cold, the spray patterns get all messed up, and the way engines correct for this is to spray a lot of extra gas into the engine to avoid misfiring. In warm weather this only lasts a couple of minutes. However, in cold weather it can be a full 10-15 minutes before the engine reaches the desired temp, which for some people is their whole commute / drive.

 

That is very consistent with what I’ve read. DI’s spray pattern is actually poor. When cold, it is far worse and requires the ECU to massively over inject fuel so enough of it can combust. The Subaru BRZ (also the Toyota 86) use both port and direct injection. When the engine is cold, it uses 100% port for better overall atomization. When warm, it uses a combination of port and DI, enough for the port to bathe the top side of the intake valves. Only under full throttle does the engine use 100% DI.

My understanding is the primary benefit of DI is that cools the cylinder, much more than port. The benefit of this cooling effect is to greatly reduce engine knock. In turn, that contributes to the very high compression ratios common in engines today. It is this higher compression ratio that increases engine efficiency and ultimately increases both power and fuel economy. Circling back to the BRZ/86, when warm and under normal load, the engineers had to find a balance of port injection to reduce carbon build up and direct injection to cool the cylinder enough to manage the higher compression ratio. It is not the spray pattern of DI that improves efficiency. It is the cooling effect and how that permits higher compression ratios. Sorry to all if this is off subject.

 

Just to be clear, the comparison was between the Outback and the RDX. The Legacy was added in there as that as also been on the same route and exceeded its highway number at speeds well above where the EPA tests. I was in no way expecting any mileage like that in the RDX, just better than what I ended up getting, 25-26 would have been nice. All my Subaru's have been complete gasoholics in city driving and the cold as they run rich when cold and idle high at start up.