I've discussed this in the past and have never gotten a real good
explanation for this, but I just came back from a 4000+kms trip through
the USA and now have some numbers to prove my observations.
In Canada, milage is reported as litres of gas per 100kms. Therefore
lower numbers are better. For reference,
7.0 is equivalent to 33mpg
8.0 is equivalent to 29mpg
9.0 is equivalent to 26mpg
In the 5 tanks of gas prior to my trip, I got the following:
If I remember correctly, the published values for my vehicle (2003 OBS)
were 7.8 for highway driving. I very rarely get numbers down below 8,
so these are pretty good numbers for me, and are very typical. 9 is
more typical for summer driving and up over 10 for winter driving.
During my trip in the states, I got the following:
On average, this represents a 10% improvement over my normal gas
milage. I'm on my first tank of canadian gas since returning from my
vacation, but I fully expect my milage number to return to "normal."
The style of driving is not significantly different. I've had plenty
of times on canadian gas where the driving was 100% highway and never
got this low before. Therefore I MUST conclude that there is something
different about american gas.
I have tried higher octane gas and have not seen any change in milage,
and therefore I do not believe there is a different in the octane
There you have it folks. Waddayathink?
Only two things that I can see to be different is you are getting different
measures of gasoline from Canadian vs. U.S. pumps or one has more energy per
unit of measure.
1. Difference in temperature compensation, although U.S. is mostly 60° equal
to 15° ATC in Canada maybe causes different volumes, would have to measure
with graduated cylinder to determine.
2. Difference in energy due to percentage of additives to reduce emissions
such as ethanol.
Only other things would be less drag due to thinner air, different
altitudes, or rolling friction on U.S. pavement.
Normally when I drive between the two countries, I purchase gas in the US
due to the lower price. I don't get to drive very fast stuck in traffic on
the 401 in Toronto so I can't really check mileage easily and compare to
open road driving.
I wonder if the mileage estimates on Canadian vs. U.S. cars are the same or
different when converted?
I just checked the 2007 Forester for U.S. vs Canada
Canada 10.7/7.5 L/100km
US 22/29 mpg or 10.7/8.1 L/100km
Odd US is rated lower on highway, maybe 100 kph vs 65 mph.
I never thought of the temperature compensation!
I know that I bought gas at Sunoco stations in the states and I saw the
10% ethanol sticker. I did a quick search but I think there is no such
regulation in Canada, therefore I believe that most of the time the
canadian gas I buy has no ethanol.
Somebody mentioned that ethanol does not have as high an energy content
so ethanol gas should produce worse milage. So the ethanol is not the
I wondered about the pavement surface too. There are more concrete
highways in the states, but the majority were ashphalt.
Oh well! There are worse things to be concerned about!
Now you are refuting your original post where you said, using numbers,
that you got LOWER mileage in the US, not better mileage. Did you
forget what you said? From your original post:
In the 5 tanks of gas prior to my trip, I got the following:
During my trip in the states, I got the following:
Before your trip [to the USA] you got an average of 8.44. In the US,
you got an average 7.55. Your mileage was *LOWER* in the US because
of the lower energy ethanol blended into the USA gasoline.
No, no, no, he already stated in his original post,
"In Canada, milage is reported as litres of gas per 100kms. Therefore lower
numbers are better."
So, the lower numbers returned when using fuel from the States represent
better gas mileage.
Oops, I see now that the dimensions are reversed: volume/length rather
I have to wonder what TYPE of driving the OP did in Canada versus in
the US. Perhaps he did lots more city driving (so gas consumption at
stops and for acceleration lowered mileage) whereas in the US the OP
did lots of highway driving or the US cities incorporated more
highways for moving around within them than the OP has in his home
area. While it's never happened for me for more than a few minutes on
US highways because there is room to pass, I've often gotten stuck
behind a slow-moving tractor on those Candadian "highways" for a long
time so mileage suffered.
We also don't know what was the humidity in home area versus when down
in the US, or temperatures differences in the air, or even what type
of gasoline he burned at home versus in the US. Hell, the OP might've
taken his car to the shop to have it prepped before taking a vacation,
something many vacationers do, and the timing got changed. Maybe his
tire pressures were low and the shop upped them (or he over-inflated
them) so his tires had less rolling resistance afterward. Tire
pressure affects mileage. Maybe with more highway driving in the US
his tires got hotter so the pressures went up so he had less rolling
resistance. We don't know how his driving habits changed when he
visited the US.
Another factor not often thought of (until the soaring gas prices) is
that some pumps measure inaccurately at higher temperatures.
According to federal data, Minnesota (my state) has the lowest average
temperature (at the time the fuel was dispensed). The pumps are more
accurate at cooler temperatures. So if the OP was fueling his car at
home when temperatures were higher then the pump's measure was more
inaccurate but in the US maybe he was filling his tank in the morning
or evening when it was cooler (than when he as refueling at home).
Gasoline expands when heated and most pumps do not adjust for
temperature. For example, in Arizona, if you buy in 5000 gallons
increments then you end up using an adjusted pump from the
distributor, but that doesn't help the lowly motorist buying 15
gallons at a time. I get a chuckle when I read Brendan Hawley's
comment (Canadian Petroleum Products Institute, Ottawa) who said, "it
doesnt matter that youre getting less volume, because youre still
getting the same amount of energy". Guess Hawley never took physics
to realize that with less volume (which not due to different pressure)
that there are less molecules in that reduced volume to burn up.
Motorists buy by volume, not by ergs or dynes. While the holding tank
is underground so the temperature doesn't vary between day and night,
that presumes a full tank. Air replaces the fuel in the tank and that
comes from above, not from some other underground cooled tank, and the
gas in the pipe and pump are obviously not underground.
While the coefficient of expansion for gasoline (0.00095 per C) is
often pooh-poohed as being insignificant, it is only when considered
alone. Say the morning or evening were 10 C cooler than mid-day. The
volume at mid-day is 0.95% larger (so you get 0.95% less at a non-ATC
pump). The *volume* has expanded by about 1% since the morning so you
only get 14.85 gallons which expanded into those 15 gallons that you
thought you got at noon. At $3/gallon for that 0.15 gallons in loss
(compared to what you would've gotten at the cooler temperature), you
lost $0.45 by pumping at noon. However, not all the gasoline you pump
into your tank will be at air temperature but then you don't know how
empty is the tank (i.e., how much atmosphere has been sucked into the
tank to warm it up versus the ground cooling it down). Half a buck
difference per full fill might not be huge but then many folks bitch
at the McDonald's counter jockey when they're off by a nickel or even
by a penny. A difference in dispensing temperature is just one part
of difference in mileage but not a major part.
There's always the chance that the gas stations at the OP's home are
simply ripping off their customers. In the US, the pumps get measured
periodically. Don't know if they check the pumps in Canada. If
there's a chance to cheat without fear of exposure or penalty then
people will do it.
Oh, forgot one other thing. Did the OP take into account the
difference between an Imperial gallon in Canada versus the
non-Imperial gallon in the US? US gallon is 3.785411784 liters.
Imperial gallon is 4.54609 liters. Just how was the OP measuring the
volume of gasoline he was putting into his tank, and was he doing the
conversion between the different "gallon" measures?
Does the Canadian gov't dictate the addition of ethanol in their
gasoline? In my state, we've been stuck with ethanol-polluted
gasoline because of legislative mandate. This was required to lower
emissions (carbon monoxide) by the federal Clean Air Act along with
the propaganda that it would reduce our dependency on foreign oil
(supposedly the 10% ethanol means we don't buy that 10% from overseas
but ethanol has less energy so we burn more of it for the same
distance so it's a wash). Now that the EPA says my state is below the
federal threshold there has been some noise about getting the ethanol
requirement lifted (because the reduction apparently was more from
less-polluting cars than from using ethanol).
About 10% of our gasoline is replaced with lower-energy ethanol.
Ethanol does not have the same energy per kilogram as does gasoline,
so adding ethanol will lower your mileage. So you end up buying
gasoline with ethanol which reduces mileage and effectively increases
your cost for refueling your car.
When you came into the US and bought gas here, you probably got stuck
burning an ethanol blend (i.e., oxygenated gasoline).
Are your equivalents done using imperial (5 quart) gallons, or US (4
quart) gallons. If you are confusing the two, that could account for
your lower apparent mileage in the US.
BTW, the conversion factor from liters to US gallons in 3.785. I'm
using this and the current exchange rate to figure out what I'm really
paying for gas when I travel in Canada.
I was actually using 3.7 litres per US gallon. If the real number is
3.785, then my calculations were 2% to the bad. So that means my
average milage in the USA was only 8% better than what I get in Canada.
This passes the sanity test since my odo was measuring significantly
more kms driven on a tank of gas than any other time in the past 4
years of owning this car.
I figured that Canadian prices translate to about $3.30USD per
USgallon! (at the time, canadian prices were $1 / litre) Prices just
dropped here by about 10%, but we're still way higher!
So, I'm still convinced that there is something about buying gas in the
USA that allows me to drive further on a tank of gas than buying gas in
My top two possible reasons:
1. The gas is different
2. The way the gas is delivered makes it hard to compare
Other reasons I don't believe, but I can't rule out:
- road surface is different
- atmospheric conditions are different enough to make a different
Thanks for the comments. We might flush out the real reason yet!
I log ALL my car expenses.
For my 2004 Forester XS, 5spd.
2006 average - 7.96 l/100km
2005 average - 8.11 l/100km
2004 average - 8.21l/100km
And I am light footed, mostly highway and running full synthetic oils. I
started using midgrade fuel during hot weather because I am able to maintain
speed up hills in top gear without pinging or lugging.
Gas mileage varies so much with driving habits, terrain, road
conditions and weather that comparisons involving small differences
like this are virtually meaningless.
With my '05 OB 2.5i, whether in the US or Canada, I can rely on on 8.0
litres/100k but sometimes get as low as 7.4 on long trips. That's
about the same as I got on my old '89 GL wagon with the 1.8 engine so
I'm very satisfied.
For practical purposes we get the same mileage on the USA west coast as
I get within BC, Canada. I keep track of all mileage on all cars ever
Several trips were with my wife's '01 Sebring 2.7L V6 and 8.0 L/100 was
the trip total over about 1,000 KMs in CDA trip and 1,100 miles in USA
trip during May.
Used the same pump for the start and end fill.
Highway at 110 Kmph about 90% of the time, slower urban speeds 10%.
FYI we have recently done a long CDN trip at 100 Kmph Max.
and got 7.6 L/100. There was an RCMP crackdown on speeding. <:)
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