Interesting MPG observations, ~4,500Kms Canada to Mexico

RF_Burns

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Sep 7, 2008
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My wife, I and the dawg left Christmas morning to drive to Manzanillo Mx. Close to 4,500Kms over 5 days in our family-truckster 2019 Dodge minivan. I reset the MPG (in our case Litres per 100 kms, I'll let you do the conversions) before we left.

This first photo is the dash display taken at Laredo Tx after about 3,000Kms on 10% Ethanol fuel. This is typical of what we see for hyway mileage in Canada (closer to 9l/100Kms because we are mostly driving 80Km/hr hyways). We filled up in Laredo before crossing into Mx to take advantage of the cheap gas. Note that from our home in S. Ontario Canada to Laredo is mostly flat with a few rolling hills. The temperature ranged from just below freezing when we left to mid 20's C when we got to the border. It was also raining a good part of the way.. I thought cool air and mist were supposed to improve MPG?

20241228-  mostly flat level terrain- USA gas.webp

Next photo below we are south-west of Matehaula Mx and running on all Mx fuel now. I reset the fuel economy display as we had been running some USA fuel mixed with Mx fuel. Also we climbed some long mountain passes requiring manual shift-downs. We filled up from near empty, so now we are running almost pure Mx fuel. The terrain here is mostly level flat plateau at about 2,000m (~6,500Ft) ASL.

I was thinking Mx gas was ethanol free, but Google says otherwise.

20241229- Mostly flat level terrain-Mx gas.webp

Next photo below we are in some large rolling hills, not mountain passes but making the soccer-mom van do some work. I did not reset the fuel economy display from above.

20241229- Mountainous terrain- Mx gas.webp

Next photo I took because the van was just about to turn over to 100,000 Kms. You can see we are climbing a good size hill.

20241229- At 99999Kms.webp

Final photo we are at our destination on the Pacific coast. So we still got 7.9l/100Kms over the last `1,000Kms in hotter temperatures and some mountain passes.

This is our 4th time driving down and I have observed much better fuel economy in Mexico every time. I know its not a GMC, but I suspect one might see improved MPG with it was well. Any ideas why?

20241229- At destination mountainous terrain-small.webp
 
I had a Chrysler minivan, other than rusting away after only 10 years and getting only 15mpg with the 3.3L iron V6, I absolutely loved that thing. It was beautiful like a wheelbarrow. You could put 4x8 sheets of plywood in the back and close the lid. So useful. They are tough to beat, the new ones get much better mileage, almost 30mpg.
 
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I had a Chrysler minivan, other than rusting away after only 10 years and getting only 15mpg with the 3.3L iron V6, I absolutely loved that thing. It was beautiful like a wheelbarrow. You could put 4x8 sheets of plywood in the back and close the lid. So useful. They are tough to beat, the new ones get much better mileage, almost 30mpg.
I bought the second minivan the local Dodge-Chrysler dealer sold back in 1984 when they first came out. It was their mini Ram-Van version with no rear side windows as I was using it for a service truck. I got lots of recall notices for it, but it never left me at the side of the road. Gutless wonder, I'm sure a frieght train had better acceleration. Held it to the floor on the 401 on the way to trade it in and got it's top speed of 75mph!

This one is a 2019 35th anniversary edition model with the stow'n go seating. Actually bought it on-line from a local dealer back home while we were in Mexico. Its been a great vehicle.
 
Its backwards to MPG, where you are measuring how many litres the engine consumes to travel 100Kms.

So the formula to convert to MPG is 62.14 / litres per 100kms x 3.78. So 6.3L/100Kms works out to ~ 37MPG, while 7.3l/100Kms = ~32MPG.

I was thinking the gas in Mx must be ethanol free, but according to Google it likely isn't, but I haven't found a definitive answer on that. We experienced the same results on a previous trip down and back home with the same vehicle.

Maybe there is some tequila in the gas!!
 
That dawned on me as soon as I saw your reply - shame on me after all those years reading Motor, Autocar, Car, etc I would remember that.
I wouldn't necessarily rely what should be there.
Their corn market was pretty much upended by imported US corn. As a dietary staple, they may be in the position of having to buy in the grain to distill or the ethanol itself, making their transportation fuel infrastructure no longer self-sufficient.
 
Is the speed limit lower in Mexico? Another possibility is that in warm climate you're driving through less dense air and perhaps that requires less power to push through it?
 
Is the speed limit lower in Mexico? Another possibility is that in warm climate you're driving through less dense air and perhaps that requires less power to push through it?
We mostly travel the toll roads which are 100-110 Km/hr (63 to 70Mph), so about the same as major highways in US and Canada.
 
windows open vs closed and running the AC?
open windows can really disrupt the aerodynamics
 
windows open vs closed and running the AC?
open windows can really disrupt the aerodynamics
We pretty much always drive with windows closed and AC when needed. Most of the way from Canada and through the USA we needed the heater in the morning, but no AC until the last day while in Texas. We needed AC through Mx after the sun warmed the air up (it was 2C when we left Matehuala Mx at about 7am).
So if anything, the AC was ON much more in Mx (where we got much better mileage) than the rest of the trip.
 
Bruce,
It's pretty clear to me that the warmer temperatures in Mexico triggered relaxation responses in you and your wife, which, in turn, triggered mechanical and hormonal responses in your vehicle in anticipation of a slower, gentler lifestyle over the winter. Which any fool could see would produce the side effect of greater mileage. I admire your curiosity regarding this phenomenon, but any of us remaining in the clutches of winter here in the northern climes can see the obvious cause and effect. I suggest you embrace another adult beverage and resign yourself to your good fortune.
 
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Bruce,
It's pretty clear to me that the warmer temperatures in Mexico triggered relaxation responses in you and your wife, which, in turn, triggered mechanical and hormonal responses in your vehicle in anticipation of a slower, gentler lifestyle over the winter. Which any fool could see would produce the side effect of greater mileage. I admire your curiosity regarding this phenomenon, but any of us remaining in the clutches of winter here in the northern climes can see the obvious cause and effect. I suggest you embrace another adult beverage and resign yourself to your good fortune.
You could be right. I think I'll just make myself another margarita and go sit by the pool... and listen to the ocean...

Pool view of ocean.webp