Increase in mileage?

Tollerowner · Oct 19, 2023

I have a 2016 CX3 with 33,000 miles. I have been getting 31.7 m/g pretty consistently, which I thought was pretty good.
Yesterday i got an oil change and tire rotation at a different place than the shop I have been using. Since then I have driven 40 miles of the typical driving the 33,000 is made up of. My mileage was 33.8 m/g. That seemed pretty strange.
This morning I checked my tire pressure and found the rear were correct, but the front were 30 psi rather than the correct 36. (I check and correct my tire pressure regularly) Wouldn't lower tire pressure reduce the mileage rather than rise it? The other shop always put 33 psi in all 4 and I had to increase the front.
The new shop wrote on the receipt that they used the correct 0w-20. The other shop never did that; I assumed they used the right oil.

So my question... could the increase in mileage be from either shop using the wrong oil?

And a somewhat sillier question... why couldn't either shop fill the tires properly. (I suppose it is possible that the second shop never checked the air pressure but from the rotation and the cold weather they were all down 3 psi)

Tollerowner · Oct 20, 2023

Today I put on 20 more miles. The computer says i got 38.5 miles per gallon today, and 35.5 over all. Perhaps bringing the front tire pressure up helped. Or maybe the computer is broken. Does that happen?

Zechariah936 · Oct 20, 2023

So my understanding and experience is, higher tyre pressure can result is lower fuel consumption, but ride quality (due to contact area on drive surface and "bounce") reduces. You find a balance that works for you, with in the manufacturer + Tyre specification.

Secondly, the fuel consumption - I prefer to pay attention to the Liters/100km, and not the L/Km.
Not sure how this is displayed in your region.

RiverMazda · Oct 20, 2023

Maybe with the cooler weather you are using the AC less?

xadagav · Oct 20, 2023

tire pressure can really change various aspects of the car

Malks · Oct 21, 2023

I don't believe the fuel mileage numbers generated by the onboard computer. They may be a good guide, but the only way to accurately get fuel mileage numbers is to calculate it yourself by how many litres/gallons you have actually put in and how many kilometres/miles you have travelled. Do this over several tank fills and you will have a far more accurate number to compare month to month.

I'm quite happy with the mileage I get on my 2016 and don't feel the need to track my fuel milage that closely.

Zechariah936 · Oct 24, 2023

Agree, best way albeit not 100% accurate is to fill the tank, reset one of the trip counters and e what mileage per tank you get. Repeat, and you'll get a good indication.
I easily achieve 720km per tank on average (without driving consciously), if I drive conservatively then it's closer to 800km.

jackpham206 · Nov 6, 2023

just comment to get pm ability

Increase in mileage?

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