American gas vs Canadian Gas

and that has exactly WHAT to do with going about 100 kms farther on a TANK of gas?

My guess is that your US miles were largely highway, and your "home" miles included more stop and go city driving.

Several explanations suggest themselves, listed in what I suspect is decreasing order of likelihood.

(1) The US trip involved less stop-and-go driving.

(2) It was warmer, and the engine ran more efficiently.

(3) The octane ratings, though nominally the same (87) differed substantially. Lower octane gas will cause the Subaru engine management system to retard the timing further, eliminating pinging but reducing power and gas mileage. I have found substantial differences in gasoline mileage between different name-brand US gasolines in my 1997 5-speedLegacy Outback (221,000 km), though all brands were nominally 87 octane.

(4) The US gas did not contain manganese additives, and the Canadian gas did. This however would be more likely to cause long-term problems with Canadian gas (catalytic converter contamination, for example -- this is why auto manufacturers dislike the manganese compounds found in most Canadian gas) rather than short-term gas mileage reduction.

Instead of resetting the trip odometer, make a cumulative record of gas purchased and odometer reading, and calculate the average km/L figure. I do this, starting a new record at the beginning of each year. The average km/L figure taken from the first of the year will be far less sensitive to minor variations in how completely you fill the gas tank than the individual km/L figures, but major changes in performance will soon show themselves as the average km/L figure begins to drift in one direction or the other. Some drift should be expected, if driving conditions (highway versus city, or time of year, for example) vary. I have on two occasions (with a 1988 Subaru GL 4x4 wagon, not the 1997 Outback) spotted a clogging fuel filter when the gas mileage began to improve markedly for no good reason. In each case it dropped back to normal when the partially clogged filter was replaced. Presumably the clogging was caused by dirty gasoline.

David, 65 km from the US border and manganese-free gasoline

On Tue, 05 Aug 2003 22:24:50 GMT, Cam Penner wrote in news: snipped-for-privacy@News.CIS.DFN.DE:

I have been getting better fuel consumption on U.S. gas for every car I have owned for the last two decades. I assume it is the composition of the gas. I always buy the regular (lowest octane) in Canada and the lowest octane available in the U.S.

Just as an example, I took a year's log and have the following numbers: (all in miles per U.S. gallon)

Average consumption for the year (includes city/highway obviously) 26.6 mpg

Best consumption for a backroads trip on Canadian gas: 29.7 mpg

Three consecutive fillups on a trip through the U.S.: 36.0 mpg 33.7 mpg 32.1 mpg

I always get better hwy fuel economy in the U.S. because everyone seems to drive faster up here.

- I usually average 120 kph on the 401

- I usually average 100 kph (60 mph) on U.S. interstates

Hence I burn about 8 l/100km in the U.S., but 9.5 l/100km in Canada...but this has nothing to do with the fuel, IMHO.

BTW, how are you calculating your tank "kilometerage", since you obviously are not driving the car dry (that might cause your fuel pump to explode (see other thread) :-) Do you just multiply the distance driven since last fill-up by the tank capacity/fuel added?

cheers!

-- Dominic Richens | snipped-for-privacy@alumni.uottawa.ca "If you're not *outraged*, you're not paying attention!"

There's only so much octane to go around, and in America we put more of it into our gas and less into our piss water beer.

Don't you think it's worth the mileage decrease to have better beer?

-DanD

Besides which, the Imperial gallon is *bigger* than the US gallon so would yield more kms per gallon, if gas were sold by the gallon in Canada.

Yes, I know. What's your point?

Who the hell would figure out their car's milage in km/gal? That's like measuring it in feet/cup.

and why is it still called "milage"? Canada isn't completely metric, we still have backyards, dog pounds and guys named Myles.

Incidentally I drove 253km on 16.044l of gas I bought at Dummond's. What works out to 37mpg or 6.4l/100km, which is waay better than anything I've ever seen published for my 95 Legacy Wagon (AWD). I was driving almost continuously at 90-100kph, which is considered the ideal speed.

I'll have to fill up with Esso next time to see if it makes an difference.

-- Dominic Richens | snipped-for-privacy@alumni.uottawa.ca "If you're not *outraged*, you're not paying attention!"