New CX-9 owner, love it, but a few gripes

Bought a 2020 GT FWD cause I love the handling, comfort, and luxury of the CX-9. Overall I'm very satisfied but I've noticed a few things and wondering if people here have similar issues or have found fixes.

1) Fuel mileage - The CX-9 sort of presents itself as a more fuel efficient SUV, but man we are only averaging around 18 mpg so far. Probably 75% city driving in Los Angeles.

2) Weak ass A/C - Takes a while to cool the cabin on a hot day. This seems to be a well known problem. Wondering if anyone has found any fixes. Tinting the front windows helped a bit.

3) Weird medium - Low pitched humming at freeway speeds 65-75 mph. I can't tell if its being caused by wind or tire vibration. Its intermittent, and does seem to depend somewhat on road surface, but also seems most pronounced at the speeds I mentioned, which is why I can't decide if its fluid or mechanical dynamics, lol.

4) Powerful but selective bass - It’s like the bass is either barely there or OVERPOWERING EVERYTHING. I saw the threads for the subwoofer padding mod so will give that a shot.

Another annoying thing....If the car is running but in park, and you want to open doors from the outside it doesn't want to let you, even if you are holding the key fob. You need to go back to the drivers door and hit the switch.

Otherwise its a great car. I'm always amazed how well it carves a corner.
 

sm1ke

Work In Progress..
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Canada
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'18 CX-9 Signature
Bought a 2020 GT FWD cause I love the handling, comfort, and luxury of the CX-9. Overall I'm very satisfied but I've noticed a few things and wondering if people here have similar issues or have found fixes.

1) Fuel mileage - The CX-9 sort of presents itself as a more fuel efficient SUV, but man we are only averaging around 18 mpg so far. Probably 75% city driving in Los Angeles.

2) Weak ass A/C - Takes a while to cool the cabin on a hot day. This seems to be a well known problem. Wondering if anyone has found any fixes. Tinting the front windows helped a bit.

3) Weird medium - Low pitched humming at freeway speeds 65-75 mph. I can't tell if its being caused by wind or tire vibration. Its intermittent, and does seem to depend somewhat on road surface, but also seems most pronounced at the speeds I mentioned, which is why I can't decide if its fluid or mechanical dynamics, lol.

4) Powerful but selective bass - It’s like the bass is either barely there or OVERPOWERING EVERYTHING. I saw the threads for the subwoofer padding mod so will give that a shot.

Another annoying thing....If the car is running but in park, and you want to open doors from the outside it doesn't want to let you, even if you are holding the key fob. You need to go back to the drivers door and hit the switch.

Otherwise its a great car. I'm always amazed how well it carves a corner.

1) In my Signature (AWD) I'm averaging around the same. I do mostly city driving, I'd say 60/40 city/highway driving. I've found that when I have the HVAC running it affects the mileage. I can get around 22 mpg without A/C running and minimal stops on my commute home. But in the summer heat, with A/C blasting and having to sit in traffic for a little while, 18 mpg is what I can expect.

2) No experience with that issue, I'd raise my concern with the dealership.

3) Also no experience there, but I would bring the issue to the dealership to see if they can remedy it. First thing to check would be tire pressures, then retorque all lug nuts, then rebalance wheels.

4) This was my experience, and the sound deadening really helped a lot. Bass is more crisp and the system sounds more balanced.

Regarding the door locks, you can configure the door lock behaviour in the Infotainment settings to always unlock all doors when the car is in Park, and to lock all doors when the car is taken out of Park.
 
Thanks for the tip on the door locks, that worked great.

I checked out the tire pressures and of course they were set at a whopping 48 psi. Bled them down to the proper pressure and it does seem like its quieted the road noise a bit. Will have to do some more freeway driving to see if it remedied the weird humming noise.
 
Bought a 2020 GT FWD cause I love the handling, comfort, and luxury of the CX-9. Overall I'm very satisfied but I've noticed a few things and wondering if people here have similar issues or have found fixes.

1) Fuel mileage - The CX-9 sort of presents itself as a more fuel efficient SUV, but man we are only averaging around 18 mpg so far. Probably 75% city driving in Los Angeles.

2) Weak ass A/C - Takes a while to cool the cabin on a hot day. This seems to be a well known problem. Wondering if anyone has found any fixes. Tinting the front windows helped a bit.

3) Weird medium - Low pitched humming at freeway speeds 65-75 mph. I can't tell if its being caused by wind or tire vibration. Its intermittent, and does seem to depend somewhat on road surface, but also seems most pronounced at the speeds I mentioned, which is why I can't decide if its fluid or mechanical dynamics, lol.

4) Powerful but selective bass - It’s like the bass is either barely there or OVERPOWERING EVERYTHING. I saw the threads for the subwoofer padding mod so will give that a shot.

Another annoying thing....If the car is running but in park, and you want to open doors from the outside it doesn't want to let you, even if you are holding the key fob. You need to go back to the drivers door and hit the switch.

Otherwise its a great car. I'm always amazed how well it carves a corner.
I too live in LA (2019 Touring FWD + Premium pkg). You got solid advice already but my experience had also been:

mileage - as low as 15mpg in heavy stop/go with AC. Typical combined 17-20. Hwy is 23-25 but can be as high as 28 if I use the cruise or actively try to ease up.

AC - yes its a weak point especially when it was 116 out. My solution is to open all the windows and hatch to vent the hot air, close it up, and go max ac with recirculation. Most importantly I get moving quickly as more rpms seem to get the compressor going faster.

Love the damn car despite the AC issues. Also, my cabin air filter was choked dirty with ash from all the wildfires. Might want to get a new one to help get a little better performance

Good luck.
 

GT4GT

2020 AWD GT, 2008 FWD GT
I had a 2008 CX-9 GT FWD which was rated at 16/22 MPG. I used to get 15 to 16 MPG while driving 60% city/40% highway.

Now I have a 2020 CX-9 GT AWD which is rated at 20/26 MPG which is 2 MPG worse than the FWD version. Now I average 21 to 22 MPG while driving 40% city/60% highway. Overall I'm happy with the MPG improvement for such a large car.

City driving for me is not stop and go traffic; it's just running errands around my house with a lot of stop lights and signs and cars.

I've read that cross-bars can reduce MPG by as much as 2 to 3 MPG. Of course running the AC does so as well.

The new car is noticeably quieter than the old car due to better sound insulation and quieter than my Honda CR-V. Maybe check your speakers for the low hum. It may be related to the Bose noise canceling feature which is supposed to activate at higher speeds.
 
:
2017 Mazda 6 Sport
Thanks for the tip on the door locks, that worked great.

I checked out the tire pressures and of course they were set at a whopping 48 psi. Bled them down to the proper pressure and it does seem like its quieted the road noise a bit. Will have to do some more freeway driving to see if it remedied the weird humming noise.
Did correcting the tire pressure help with noise?
 
I had a 2008 CX-9 GT FWD which was rated at 16/22 MPG. I used to get 15 to 16 MPG while driving 60% city/40% highway.

Now I have a 2020 CX-9 GT AWD which is rated at 20/26 MPG which is 2 MPG worse than the FWD version. Now I average 21 to 22 MPG while driving 40% city/60% highway. Overall I'm happy with the MPG improvement for such a large car.

City driving for me is not stop and go traffic; it's just running errands around my house with a lot of stop lights and signs and cars.

I've read that cross-bars can reduce MPG by as much as 2 to 3 MPG. Of course running the AC does so as well.

The new car is noticeably quieter than the old car due to better sound insulation and quieter than my Honda CR-V. Maybe check your speakers for the low hum. It may be related to the Bose noise canceling feature which is supposed to activate at higher speeds.
I would say if you live in flat area with gentle driving with idle stop on - you may only lose 2-3 MPG. However, if you are living up in a hilly suburb with more city driving (like 60% city) - you could almost half the stated MPG. I am getting 16-18MPG with 80% city 20% highway driving and I live up on the top of the hill. I hate idle stop so mostly turn it off.
 
On my Signature I only use for traveling and on freeway w out camper I get about 25 MPG in flat areas, also I use non ethanol not sure if it makes any difference.
As far as the humming sound it might be something simple as rotating tires.
 
:
2020 Mazda6 GTR
I have the same vibrating issue with my 2021 cx-9 signature I bought only a week ago. Already had it to dealer, they said it could be due to flat spots on tires from sitting too long due to C19. I'm not buying that reason at all since the car was just driven 300 miles to the dealer where I bought it. I had test drove other cars same as I bought (no vibration), but dealer had to locate my color combo so I never test drove the car I bought (my bad I know). In reading some other blogs about this same issue I didn’t see any real consistent solutions. I love the car except for this issue. I notice it most at 35 to 45 mph and at 65 to 75 mph. The sun visor visibly shakes when it's down and side mirror vibrates. My 2018 Toyota RAV4 that I traded drove smoother than this. So bummed!
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
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'18 CX-9 Signature
I have the same vibrating issue with my 2021 cx-9 signature I bought only a week ago. Already had it to dealer, they said it could be due to flat spots on tires from sitting too long due to C19. I'm not buying that reason at all since the car was just driven 300 miles to the dealer where I bought it. I had test drove other cars same as I bought (no vibration), but dealer had to locate my color combo so I never test drove the car I bought (my bad I know). In reading some other blogs about this same issue I didn’t see any real consistent solutions. I love the car except for this issue. I notice it most at 35 to 45 mph and at 65 to 75 mph. The sun visor visibly shakes when it's down and side mirror vibrates. My 2018 Toyota RAV4 that I traded drove smoother than this. So bummed!

Get the dealership to do a wheel alignment to rule out unbalanced wheels and also to retorque lug nuts to spec. Then get a second opinion from a tire shop about the flat-spotting and whether 300 miles is enough to work the flat spots out. We've had a lot of similar reports in the CX-5 forum and the tires seemed to be the culprit - but in many of those cases, the vibration would go away after a few miles of driving, and return if the car sat for too long (tires were flat-spotting overnight). Doing a bit of reading online, it seems that temporary flat-spotting resolves itself after 5-10 miles. Apparently if the vehicle sits long enough, the flat-spotting can become permanent. If that is the case, push for new tires from the dealer. If they say it'll resolve itself after XXX miles, get them to put it in writing (stating that you want new tires if this issue doesn't resolve itself after XXX miles). If the flat-spotting is now permanent, I would at the very least want compensation for tire replacement.

Vibration at those speeds is not normal for this car, I would not roll over on this. Do what you can to get them to fix the problem. If you can't get satisfaction from the dealer, go over their heads and contact Mazda Corporate for further assistance.
 

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