Low MPG on used '14 CX-5

From http://www.cleanmpg.com/community/index.php?threads/14198/

"With a little playing around air at about 10 degrees is about 20% denser than air at about 95 degrees. I figure that in terms of air resistance to you car as you drive that is about equivalent to increasing the speed by about 20%.

The effect of changes in humidity seems to rather small."
 
The OP hasnt stated what his tyre pressures were, or if he has checked and adjusted them recently. If they were down around 30-32 then there would most certainly be a measureable effect on fuel economy. And as we know, tyres naturally lose pressure over time, and may not be immediately obvious.

So, it is wise to regularly check tyre pressures because running low pressures is one of the most common causes of poor fuel economy - people often overlook the simple things in search of more complex causes.

Air pressure affects rolling resistance. Sidewall deflection etc.

Get a pushbike and ride it with tyres at lower than optimal pressure and see how it goes. Then pump the tyres up hard. Easier to get up to speed and keep there, and rolls further.

Same reason that car manufacturers recommend higher pressures when carrying a load.

Its physics 101.

On the 225/55/19's Mazda here recommends 36psi all round light, and 38 front/42rear loaded. See attached tyre placard from my car.

So running 38/40 all round is no stretch at all.
 

Attachments

  • IMG_1304.JPG
    IMG_1304.JPG
    935.4 KB · Views: 92
Last edited:
This is a quote from MB forums about the B-Class electric which has a Tesla powertrain : "B Class will do 70-110 miles. 70 is bad winter weather and 110 during summer"
The winter performance drop is a significant reason why folks in northern parts hated their Nissan Leaf that would lose up to 25% of range due to battery degradation and then some due to winter. Electrics always lose range in winter.
Your car works harder in winter to overcome the dense air - wind resistance is a big factor at 60 mph and above - hence you can see studies that say close your windows at that speed and turn A/C on.

In theory bad winter should affect mpg adversely by 1-2 or more. This is true in practice as well.


Anyhow back to the original question - while doing steady driving, lets say you are on a road with speed limit 45 and no traffic - you would do 50 or so and put on cruise etc. - do you use the paddle shifters to go a gear up and improve FE? .

The engineers have the tranny programed to maximize MPG at every throttle position. Lowest possible RPM is NOT always the highest MPG. But you can have a lot of driving fun by trying this.

BTW, I tried this with my Impreza with CVT and paddle shifters. I drove 60 minutes one-way on empty county roads, so could duplicate driving conditions. Manually shifting resulted in less MPG, and the Imp reved WAY higher than I thought was appropriate for light accel.
 
The engineers have the tranny programed to maximize MPG at every throttle position. Lowest possible RPM is NOT always the highest MPG. But you can have a lot of driving fun by trying this.

BTW, I tried this with my Impreza with CVT and paddle shifters. I drove 60 minutes one-way on empty county roads, so could duplicate driving conditions. Manually shifting resulted in less MPG, and the Imp reved WAY higher than I thought was appropriate for light accel.

I like watching the instant MPG read-out while accelerating smoothly. It actually goes UP as the rpm's go up in some gears.
 
I've had a 2013 CX5 Touring 2.0, and now a 2015 CX5 Touring 2.5. MPG on the 2013 over 27,868 miles was a low of 22.3, and a high of 34.8, with an average over the ownership of 29.0. The 2015 over 28,687.7 has had a low of 21.4, and a high of 33.1, with an average over the 27,868 miles of 28.20. On the 2015 I also have kept track of the dash readout. It showed an average of 28.5, so the difference between measuring at the pump, and the dash readout is negligible. Both were fwd, and I have paid little attention to the tire pressure except to check it once in a while.
 
The engineers have the tranny programed to maximize MPG at every throttle position. Lowest possible RPM is NOT always the highest MPG. But you can have a lot of driving fun by trying this.

BTW, I tried this with my Impreza with CVT and paddle shifters. I drove 60 minutes one-way on empty county roads, so could duplicate driving conditions. Manually shifting resulted in less MPG, and the Imp reved WAY higher than I thought was appropriate for light accel.

You are rarely going to out perform a CVT. But the Mazda has a traditional 6 AT. I know it spends about 80% in TC lockup but still you can try to push through gears faster than the normal would be - this may not give you a ton of mpg improvement but can be forgiving for those who dont want to precisely control throttle input. Also there is merit in dropping gears while slowing down to see if engine braking works to help FE.

Overall - difference between my Camry 2015 and CX-5 is 1-2 mpg. I drove camry to work today - drove hard and got 28.1 mpg. If i drive CX-5 similarly - I think i would get 26 or so. My commute is 7 miles through city so trying the paddle may be more beneficial for me.
 
You are rarely going to out perform a CVT. But the Mazda has a traditional 6 AT. I know it spends about 80% in TC lockup but still you can try to push through gears faster than the normal would be - this may not give you a ton of mpg improvement but can be forgiving for those who dont want to precisely control throttle input. Also there is merit in dropping gears while slowing down to see if engine braking works to help FE.

Overall - difference between my Camry 2015 and CX-5 is 1-2 mpg. I drove camry to work today - drove hard and got 28.1 mpg. If i drive CX-5 similarly - I think i would get 26 or so. My commute is 7 miles through city so trying the paddle may be more beneficial for me.

It spends about 99% of its time in lock-up unless you;re <10mph, I thought,no? It is NOT a conventional 6A.
 
Back