2016~2023: Improving/maximizing fuel economy

[sm1ke]

A recent road trip prompted me to create this thread. Some info about the car and trip:

• 2018 AWD
• 125k kms (78k mi)
• Bridgestone Blizzak DM-V2 tires inflated to 38psi, on OEM 20" wheels
• Family of 4 (2 adults, 2 toddlers) plus approximately 100lbs of additional cargo
• Average cruising speed of 80mph on the highway
• A/C running at low for half of the trip, otherwise only fan was running
• No roofrack or wind deflectors installed
• Alignment was recently done and is within spec
• The only modifications to the car at the moment are a CorkSport air intake and CorkSport lowering springs
• Engine air filter hasn't been properly cleaned in about 20k mi
• Spark plugs were recently changed at 120k kms
• Approximately 7000 kms on oil (Kirkland Signature 5W-30)
• Weather conditions were clear and dry, but there were some strong crosswinds and gusting occasionally
• Average temps ranged from 2c to 10c
• Used a mix of 87, 91 and 93 fuel during the trip

Average fuel economy was 20.5 mpg during the entire road trip (90/10 highway/city). My typical city focused driving is usually closer to 17.5 mpg. Now, EPA figures are 26 highway, 20 city. This is much better than the actual fuel economy I'm getting. Looking back on the info above, it makes sense that I'd experience a hit to fuel economy thanks to the tires, extra load, dirty air filter and mileage on the oil - but is a 5.5 mpg loss reasonable?

I plan to change the oil and clean the air filter in the next few days, but is there anything else you guys would recommend changing/cleaning?

 

[N7turbo]

Unless you were going through a mountainous area, or the car was significantly loaded down, it seems low to me.

If this is a sudden change, some culprits could be bad gas (unlikely), extra weight, or the snow tires.

A slower degradation: possibly an intake cleaning is in order.

As an aside, I'd like to make some wheel covers for aero on trips but I'm not sure where I'd start.

 

[Silly Wabbit]

I think I read somewhere that each 100# = 1mpg. So the extra occupants + cargo would yield -2 mpg. Also, the EPA estimate was likely achieved at lower highway speed and so I think considering everything, your 5mpg hit was reasonable

 

[Mazdiod2]

The cooler temperatures and the wind gusts can make a difference, too. Especially if there are also sustained winds, unless they are behind you.

 

[hw4ng3r]

Are you reporting round trip numbers there?

And don't forget, Peg to Cowtown is an elevation change of almost 3000 ft (just not sure how steep, if at all, any of the stretches of that is since I've never driven it).

Best I've ever recorded is 25 mpg @ 90 km/h on cruise for a stretch of 550 km of relatively flat driving in the summer. Two adults + a toddler (2 years old), ~50 lbs of extra cargo, with A/C running.

My daily driving is in Toronto (99% city driving) and I usually get 19.5 mpg.

Edit: You said entire road trip so ignore my first question

 

[sm1ke]

Elevation was one thing I forgot to mention, there were some hills and valleys. Nothing too steep, and the engine RPMs never went over 3.5k even on inclines. Fueled up at Shell and Petro Canada stations mostly, but the single tank of 87 was from an Esso.

Thanks for all the feedback guys. It seems most likely that the culprits are the air filter, winter tires and extra load, paired with elevation changes and wind. I feel a little bit better about the numbers now, much appreciated! My cousin bought a CR-V Hybrid while we were visiting, I think I was just more conscious about fuel economy coming home because of the fuel economy he was getting with his new car.

 

[Silly Wabbit]

Comparing with hybrid is frankly apples to oranges. If it makes you feel better, one thing the crv can't achieve is to seat 7(or 6).

 

[MichalP]

My little input. 2 years old CX-9, 30K at that time. Summer driving, 4 adults+2 kids, loaded as much as possible (lots of bottles of wine in underfloor compartment ) - BC/Alberta trip with some mountain passes in BC and lots of flat driving in Alberta . My average at that time: 31 mpg (7.5 L/100km). 100-110 km/h speed with lots of coasting/engine braking.

Current city mileage (like 90% in the city - morning commute to work): 20.5 mpg (11.5 L/100km).

General approach: no heavy acceleration and lots of coasting if possible (this car can roll and roll and roll w/o any gas)

 

[Lazy2.5]

A common hypermiling technique is to use slightly more throttle going down hill (Where you are in an advantageous position to gain momentum,) And to back off the throttle while climbing hills (Where you are not in an advantageous position to gain or hold momentum.) This helps with MPG by keeping engine load within a specific threshold, negating the need to downshift, and to simply wait for the next section of downhill to gain your speed back instead. With this habit, you can certainly improve that figure, so long as you are prepared to patiently lose some speed on certain sections of road.

The other tip would be to get up to speed slowly and pay attention to the vehicles shift points. Don't exceed the shift points which the transmission desires unless you it need to. It might seem painfully slow, but avoid the heavy/excessive acceleration, and patience will go a long way. I hardly ever am on the road without encountering some impatient driver who speeds past me, only then to stop up ahead and have me catch up to them anyways. happens nearly everytime i drive, so i stopped accelerating so uselessly and save lots of gas.

Another tip is to always maintain a large following distance from the car in front. Not just for safety, (Logical, and not the purpose of this conversation.) But, because you often don't have to brake whenever there is a slowdown ahead, assuming your following distance is sufficient. this helps to maintain a more steady average speed; good for fuel economy.

This general advice points towards two things: Be patient and focus on keeping a steady pace, minimize the use of excess acceleration, which helps avoid braking excessively too.

Keeping the cruise control set to 80mph, especially while climbing a hill will cost you too much gas. if i anticipate a downhill I'll be easy on the throttle until I reach the crest, then begin to accelerate on my way down.

While i'm doing this, I pay close attention to the real time fuel economy read out. I never drive without following it closely. Throwing out specific numbers will be useless to you, because we do not drive the same car, so I will say this: simply focus on maintaining a certain range, (eg, between 5-7L/100km, backing off the throttle when you exceed the target you've set for yourself)

As mentioned before, with this advice, I get fantastic fuel economy, but I do drive quite slow at times to maintain it.

 

[youri]

Your average speed is the issue. At 80mph in the CX-9 the 6th gear is geared too low and the revs are pretty high. It consumes a lot more. I tested it one day, the difference between 90km/h and 100km/h was about 1l/100km and between 100km/h and 110km/h was about another 1L/100km.

Usually at 115km/h (70mph) if i recall correctly i think i was getting about 9L/km (26mpg) (on flat terrain). At 80 mph you were travelling at about 128km/h.

Also the faster you go the harder it is to push the air around the car. The additional drag from 10 more mph from 70mph to 80 mph is a fair bit higher than from the same 10 mph from 50 to 60 mph. The faster you go the higher the fuel economy penalty. But you saved 3 hours of driving

 

[PTguy]

The air filter doesn't hurt the gas mileage. A dirty filter with higher resistance just means that the throttle butterfly doesn't have to close, throttle, the induction air as much. What harm does a dirty air filter do? It limits the top end power. Think of having a pebble under the accelerator pedal so you only get 95% max instead of 100% max.

For lower fuel consumption run on summer tires, lighten the load as much as possible, and slow down. The drag force is proportional to the square of the object’s speed.

 

[sm1ke]

Thanks guys, appreciate the insight! I knew the speed would affect my fuel economy, I just didn't realize how much.

I filled up at the Shell I always go to yesterday. A nice surprise - they now stock 93! They must have added it to the station over the weekend because 91 was the max when I fueled up for the trip on Thursday. I was going to sell my JB4 because I had to remove it for a warranty issue, but now I think I might reinstall it and keep it lol.

Since filling up, I've tried to apply some of the tips you guys suggested, and they definitely improved my economy just over my last couple of work commutes. Again, I appreciate the suggestions everyone gave

 

[Lazy2.5]

Thanks guys, appreciate the insight! I knew the speed would affect my fuel economy, I just didn't realize how much.

I filled up at the Shell I always go to yesterday. A nice surprise - they now stock 93! They must have added it to the station over the weekend because 91 was the max when I fueled up for the trip on Thursday. I was going to sell my JB4 because I had to remove it for a warranty issue, but now I think I might reinstall it and keep it lol.

Since filling up, I've tried to apply some of the tips you guys suggested, and they definitely improved my economy just over my last couple of work commutes. Again, I appreciate the suggestions everyone gave

Nice, what sort of improvements did you apply and how did it help to improve your fuel economy?

 

[Lazy2.5]

I thought about starting a general thread where we can share tips for responsible driving, (ie. 1 safety tips, 2. maximizing efficiency.) But remembered this thread. @sm1ke what are your thoughts on creating such a thread where experienced drivers can share tips that help maximize driving safety and efficiency?

 

[Lazy2.5]

With the cold weather here in central Ontario coming in, I have noticed an approx. 0.2, 0.3L/100km increase in fuel economy.

I mostly attribute this to the torque converter being unlocked during the first 5 minutes of driving on a cold start, on top of the fact that the long term fuel trims are quite rich (around 10% from what I remember) until the blue coolant light shuts off.

Therefore, anytime the vehicle is cold, especially if it is cold enough for the torque converter to remain unlocked (Floating rpm's, higher rpm's during the first 5-10 min of operation) it is particularly important to be very gentle on the throttle during this period, both for the sake of drivetrain protection and fuel efficiency.

I find that keeping rpm's below 2000rpm during this period and simply focusing on maintaining a set speed is particularly important during the warm up process.

Once the blue coolant light turns off, you can start to use a bit more throttle, though the car doesn't seem to like that idea...

 

[Agape_365]

I average 12.9l/p100 or 18.1 mpg with my average load including trailers over 4000km using 87. I am contemplating trying 93 for 1000km to see if that changes much of anything.

But this thread was a good read

 

[sm1ke]

I thought about starting a general thread where we can share tips for responsible driving, (ie. 1 safety tips, 2. maximizing efficiency.) But remembered this thread. @sm1ke what are your thoughts on creating such a thread where experienced drivers can share tips that help maximize driving safety and efficiency?

I think that's a great idea. It would probably be best to post in the Lounge section as it sounds like the majority of the tips would not be model-specific.