Mile Per Gallon!!!!

[bill42]

Is yours 2 wheel drive maybe? Or maybe some of you guys have some sort of super gas jet fuel at your gas stations. Or is it because you have God on your side? ;-)

I just completed a 350+ mile highway trip to Canada. I do have a new Thule Cargo box on the roof that surely cuts down on gas mileage at highway speeds. I filled up the tank at the start of the highway driving. I never went over 80 and 90% of the time I was driving my fully loaded CX-9 AWD at 70mph. At the end of the tank I calculated 13.5 mpg, 100% highway driving.
It must be that the cargo box costs me a lot of extra fuel, but could it be causing me to lose 7 miles per gallon? In the past I average 18.5 for all highway driving.

 

[jabba]

Back from a road trip over Xmas, ended up with 19 mpg with mostly highway driving. Same trip over the summer ended up with 22 mpg.

So winter driving hurts the beast, but I was expecting that. Half and half driving ends up somewhere near 14 mpg, usually about 16 in the summer.

I wouldn't say that this is great mileage, but again, I bought this thing knowing what I was getting myself into. The weight just kills you. I do have to admit that it's a bit worse than I was expecting, we've really been babying the beast...ah well.

 

[CX9 SportOwner]

as in my signature, 2 wheel drive, but that's only 1 or 2 mpg difference at best. Also, keep in mind the boat we carried. not as aero as your thule box, and probably heavier, too

 

[bill42]

My post drive conclusion:
I had about 200 pounds of gear in the roof box, plus another 200 in the back, plus 500 pounds of humans. With the extra ~1000 pounds of weight, my CX-9 was about the weight of a Suburban-sized vehicle, and I would guess with not much better an aerodynamic profile. Therefore, it makes sense—nothing in this universe comes for free. If you are the weight of a large Suburban, you are going to get roughly the same mileage as a Suburban.
On my return trip with no snowstorm, I got closer to 15 or 16 mpg, just like a large sized SUV gets on the highway.

 

[tomiller97]

Seems that our fuel economy is common across the country. I live in Ohio and drive an 08 FWD Sport CX-9 and have averaged 16mpg over the first 4500miles. My wife normally drives it and does a majority of city driving.
I've kept track of every tank so far and the best we've done was 19 (that was with me driving it to work from Toledo to Detroit for a few days 60 miles one way at about 75mph). I haven't seen much fluctuation in economy over the first 3 months we've had the vehicle due to "breaking in" either.

I also haven't made it a point to use 'better' gas, say only going to Sunoco or a Mobil station vs going to the cheapest gas in the area. I normally use gas from Kroger as we get a 20 cent discount per gallon. I've always only used regular 87 Octane to this point as well...

 

[Asia]

Want a good laugh? We have only had our CX-9 a couple weeks and when we went to pick it up, our salesman wasn't there yet. Another saleman came over and talked to us until he arrived. He said he owned a CX-9 and that after the "break-in" period of about 8k miles, he gets 29 mpg on the highway. I figured he was embellishing a little!

 

[bill42]

sounds like some people on this board actually...
just kidding. Mostly.

 

[SeCX-9]

I'll bet he has his family of 6 who usually sit in the back, get out and push the car about 7 more miles per gallon....

 

[Asia]

First tank with 300 miles on the car we got 18 mpg in mostly suburban driving, some back country roads. FWD Sport with no roof racks.

 

[Padre Dave]

Got my best tank yesterday with 23.6 mpg....way cool. She likes Chevron Regular the best....hates "no-name" gas like at Costco.

 

[not_too_shabby]

23.6. wow. you must have a light foot. The warm weather probably helps as well. Cold air is denser = more fuel.... I'm still bouncing around 15 MPG in mixed driving.

 

[cccx9]

I get about 18 with mixed driving on cheap costco gas with my AWD.

 

[o.c.cx9]

What a gas hog

Filled up today at Costco 14 + Gal on all city driving and not hard driving.

Whoopee 11.7 MPG.

Hope I can find a sucker this year to buy it.

Tom

PS. All of you who claim 18MPG in the city.
Well(butt)

 

[bill42]

you are not alone. I drive mostly all city driving in NY and I get 230 miles on a full tank and no more- in the high 11's. The people who get 18 would get 11 instead if they drove in my city for a week. I have no hole in my gas tank. CX-9s don't roll off the assembly line with every other engine dropping 6 mpg.

I am sure if I had a big Chevy Tahoe or an Escalade I would be getting 9s.
I don't complain anymore- I just accept it. I need the 3rd row seat and I can't think of another SUV other than a hybrid that would be any better. With the hybrids you simply pay the fuel savings difference upfront.
The CX-9 still wins.

 

[jpr210]

I think that once someone goes to the dyno with one of these CX-9 we will discover that the thing runs very rich and a good tuner will be able to lean it out and get much better millage and more power to boot. is there anyone out there working on this?

Jpr

 

[bill42]

I think that once someone goes to the dyno with one of these CX-9 we will discover that the thing runs very rich and a good tuner will be able to lean it out and get much better millage and more power to boot. is there anyone out there working on this?

Jpr

I am curious as to why you might think this? With 273 hp and 270 lb-ft of torque rated at the engine, the 3.7L engine in the CX-9 has more power/liter than my 1999 BMW M3 had, and that engine required 91 octane.
How much power do you think someone can get out of a 3.7 liter with no forced compression and standard 87 octane? Our engine beats most of the competition in its class as well. I think Mazda hired better engineers and spent more R&D on this engine than any tuner could ever afford. Yes, a tuner can build a new engine map and sell you a new chip to get more horsepower but that would require switching to high octane fuel and also raising the redline, giving the CX-9 even worse mileage.
Also, if the engine was running rich it would produce more carbon and fail emissions. In modern engines with all the precise sensors, fuel mixture is precisely controlled to a level unheard of 10 years ago, and engines are both more powerful and more efficient than ever before as a result.

 

[CX9 SportOwner]

Got my best tank yesterday with 23.6 mpg....way cool. She likes Chevron Regular the best....hates "no-name" gas like at Costco.

Gas is gas. It's literally all the same, because every refinery puts a specific volume of gas in the pipeline, and is allowed to take that much out of the other end, never knowing who actually manufactured it. So they all make the exact same product. It has to be the same chemical composition in order to BE gasoline.
The only difference at the pump is that companies like Shell and Chevron then put additives in their gas prior to trucking it the their stations claiming it helps keep your engine cleaner. The truth is, it's just cheap filler to give you less actual gasoline per gallon for your money. What keeps an engine clean is efficient combustion, and you get that with undiluted gas. Every vehicle I've owned ran worse on Chevron because of the junk they add.

 

[bill42]

Not just shell and Cevron, but I think all the companies add extra additives and levels of Ethanol. When tested, many gas stations have been proven to not meet their advertised octane rating. In the old days before electronic timing, I used to buy bad gas sometimes from cheep places and my old Chevelle would ping like crazy. In modern cars we don't notice the bad gas because our cars simply retard the timing.

 

[treeguy4u]

We have checked ours twice in the last month and got around 14mpg with 1600 mi. on the car. Little discouraged but not giving up yet. My wife drives the car most of the time. I think that's where at least 5 mpg are going. Traded in Toyota Avalon that was getting 20-22 city/highway. But I love doing in the snow what that FWD Avalon cannot do. Lots of good ideas on this forum for getting better mileage.

 

[jpr210]

I am curious as to why you might think this? With 273 hp and 270 lb-ft of torque rated at the engine, the 3.7L engine in the CX-9 has more power/liter than my 1999 BMW M3 had, and that engine required 91 octane.
How much power do you think someone can get out of a 3.7 liter with no forced compression and standard 87 octane? Our engine beats most of the competition in its class as well. I think Mazda hired better engineers and spent more R&D on this engine than any tuner could ever afford. Yes, a tuner can build a new engine map and sell you a new chip to get more horsepower but that would require switching to high octane fuel and also raising the redline, giving the CX-9 even worse mileage.
Also, if the engine was running rich it would produce more carbon and fail emissions. In modern engines with all the precise sensors, fuel mixture is precisely controlled to a level unheard of 10 years ago, and engines are both more powerful and more efficient than ever before as a result.

Mazda, like other manufacturers make the engines run slightly rich as this cools down the conbustion chambers, keep the engines cool under extreme circumstances. A slightly rich combustion keeps the engine more tolerant of different types of gas quality and able to perform well in both the 90 plus degree heat as well as below zero. When a good tuner tunes an engine on the dyno as well as live on the road, they are able to adjust the engines operation of the particular area and gas quality you can get. My Chev LS1 with a tune got 20 more HP and 3 more MPG from a on site tunning (not a mail order chip).

That is just my experience.

Jpr