Gas mileage, how to improve?

K&N air filter may get me a few more but what else you guys doing? Using high test, taking all the extra weight out of the car?
No, No, Yes.
The air filter is putting a resistance in the intake exactly like a partly closed throttle butterfly does. Any filter does absolutely nothing for gas mileage. It does absolutely nothing for power except a clogged filter at max rpm and full throttle will act like a not-quite-wide-open throttle. Anyone who says that any so-called high performance filter will save you gas is lying to you. The exception...an old carbureted engine without electronic controls will run rich with the clogged filter. I don't know anyone still driving one.

High anti-knock index gasoline may give a fraction better miles per gallon but is a loser at cost per mile.
 
I am averaging about 24 MPG in a 2018 CX-9 and it is getting better everyday. I think I will end up somewhere around 24.5 to 24.7 after another 20K miles. For a car this size, I will take 25 MPG any day. Can easily get 28-30 MPG when driving on the highway if I go the speed limit plus 5. 80 MPH drops gas mileage dramatically.
 
Without over revving, get to your highest gear and maintain the lowest rpm. That will be your most economical speed. Once you figure that out, I try to to get to that speed (whenever possible) and you would be surprise on how much your mpg goes up.
 
Lighter wheels & tires will accelerate quicker and brake better (rotating weight has more influence than dead weight). Once up to speed they don't make any difference.

Low rolling resistance tires don't have an industry standard spec. They're whatever the tire maker wants to call them. From a retired tire engineer:
--quote--
Most rolling resistance is caused by internal friction of the rubber as the rubber moves through the footprint area.

1) The more the tire deflects, the more the rolling resistance. This is more or less a "load vs inflation pressure" kind of thing.

It ought to be obvious that as you add more inflation pressure, its effect on the deflection decreases - meaning that adding 1 psi over the placard inflation pressure has much more effect than the effect between 5 psi to 6 psi over the placard pressure.

2) The more the material in a tire - especially in the tread area - the more the rolling resistance.

This means that new tires are going to have more rolling resistance than otherwise identical, but worn out, tires. So when you buy a new set of tires, you should expect a loss in fuel economy.

This also means that all terrain tires, winter tires, mud and snow tires, and off road tires are going to have more rolling resistance than a comparable all season tire.

This also means that higher speed rated tires - with their additional cap plies - are also going to have higher rolling resistance.

3) The tread compound - and the amount of internal resistance it has to movement - is going to have an effect on rolling resistance.

There are three properties that can be traded off with one another - Tread wear, Traction, and Rolling Resistance. You can maximize one of these properties, but it has to come at the sacrifice of at least one of the others.

This means that tires with good traction compounds have either sacrificed treadwear or rolling resistance (or both). This also means that tires with high UTQG treadwear ratings have sacrificed traction or rolling resistance.

--end quote--
http://www.barrystiretech.com/rrandfe.html
 
I have a 2017 CX 9 GT, AWD. 27,000 miles on it. Just did a 3,000 mile road trip from Southern California to the Tacoma, WA area and back. I reset my mileage just as I left the house and averaged 24.7 MPG overall. I did alot of freeway driving (Interstate 5 around 75-80 mph), alot of hills/mountains driving through Tahoe to Reno, through Oregon (Mt. Hood area), down 101 and through the Redwoods. I think it is a broad range of driving environments. I'm pleased with the mileage. Car was loaded down with several suitcases, a cooler, and my mountain bike on the hitch/rack.

Love the CX 9, very comfortable to drive. I did have to do a big detail job when I got back to get all the bugs off the front!
 
I can get as high as 27-28mpg with my 2019 T AWD, if I go really easy on the loud pedal. That is amazing with a 4300 lbs SUV. What was also surprising is that the dash trip computer MPG estimate is very close to actual calculated MPG when I gas up. Last fill-up of 15.01 gal went 407 miles, which calculates to 27.1 mpg. Dash showed 26.9 mpg for the same duration. This is the only vehicle I have driven EVER that showed a displayed MPG lower than actual. Most other vehicles are typically overly optimistic by 1-2 MPG, sometimes 3.

I've been driving V6 SUVs and minivans of similar size for the past 15yrs and was a bit apprehensive about "downsizing" to a 4cyl. I test drove a Buick Enclave 3.6L V6 and Infiniti QX60 3.5L V6 and the Mazda had by far the best powertrain. Buick's 310HP looked impressive on paper, but was disappointing in actual driving. I'd step on the accelerator, and the tranny would immediately downshift to shoot RPM right up to 5-6k RPM, jerked the chassis, made a lot of noise, but didn't produce a really strong push to speed up the vehicle. Mazda OTOH stayed low in the RPM and just let the 310 lb-ft of torque pull the car steadily in a very composed manner. Even my wife sitting in the passenger seat commented on the stark difference.

The QX60's powertrain felt more refined than the Buick, but I did not like that they made the CVT imitate the stepped RPM characteristics of a conventional geared tranny. It would've been a lot better if they had let the CVT do what it does best - varying the ratio continuously to keep the engine RPM at the optimum point, for either best performance, or best efficiency. But I guess enough uninformed drivers complained about the "odd" feel of a CVT, that Infiniti felt they had to fake the CVT into behaving more like a geared tranny. Going by the EPA ratings, I doubt QX60 AWD can match CX9's mpg in similar driving.

Overall, I'm really pleased with the CX-9's drivetrain. It felt every bit as smooth as the V6's I've driven previously and is more efficient to boot. Exactly what I had hoped.
 
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