MPG run, part deux

[TominMO]

Not to rain on your parade or anything, but you *really* have to run through at least 1/3 to 1/2 a tank to get an accurate mpg number.

I dont doubt at all that you could push 60 mpg running 45 down the highway, I mean I got 53 mpg doing 60 on the interstate (limit was 70, people were doing 75-80)... its just that you cant get a truly accurate number using so little gas.

I am confident in these numbers, because I was very careful in both fillups. Granted, more mileage would give more confidence in the result, but I still feel it was valid. The only crucial factor is to make sure you re-fill the tank to where it was before. As I mentioned, when I refilled the tank, I was careful to get in every drop I could.

I've seen mileage tests on TV, Mythbusters for example, where they use a measured amount of gas, like one gallon, in a small separate container. When it runs out, that's their MPG figure. That seems valid to me.

[bhazard]

Not to rain on your parade or anything, but you *really* have to run through at least 1/3 to 1/2 a tank to get an accurate mpg number.

I dont doubt at all that you could push 60 mpg running 45 down the highway, I mean I got 53 mpg doing 60 on the interstate (limit was 70, people were doing 75-80)... its just that you cant get a truly accurate number using so little gas.

[JPT]

Very interesting though, looking forward to seeing what you get at 55.

[TominMO]

Nice numbers, but they would be hard to keep up over a whole year.

45 on the highway?

Around here, you would either be a dead man or the cause of the daily crash. People fly down the road in all the lanes, the fast lane averages around 90 in the morning (at least 'til you get up around Boston). Even little old ladies would run your butt over.

Quite a few accidents caused by people not looking when going around slower cars.

Since the year started, I'm an eye witness to two of these.

I fully agree with all your points; no way would I drive that way normally. This was a one-time deal, and why I did it early Sunday morning. That's why my next run will be at 55, also early on Sunday.

[JPT]

Nice numbers, but they would be hard to keep up over a whole year.

45 on the highway?

Around here, you would either be a dead man or the cause of the daily crash. People fly down the road in all the lanes, the fast lane averages around 90 in the morning (at least 'til you get up around Boston). Even little old ladies would run your butt over.

Quite a few accidents caused by people not looking when going around slower cars.

Since the year started, I'm an eye witness to two of these.

[TominMO]

Yeah, me neither. Just curious if those results could be replicated over a whole tank. Say 400 miles or so. Don't really see why they couldn't. Just more stupid curiosity than anything.

Theoretically you could get over 600 miles per tank. Five tanks gets you from NY to CA!

[batstiva]

Ten gallons of gas is less than 80 lbs, so I doubt that it really matters.

Yeah, me neither. Just curious if those results could be replicated over a whole tank. Say 400 miles or so. Don't really see why they couldn't. Just more stupid curiosity than anything.

[TominMO]

Ten gallons of gas is less than 80 lbs, so I doubt that it really matters. But if anything, mileage should get better as the car gets a little lighter. It was hard to go that slow, especially when everyone else was going a lot faster.

[batstiva]

Did another MPG run today. Took out the rear and passenger seats, folded in the right side mirror. This so I could simulate less gas in the tank, and an L model.

I drove a 75-mile loop around St. Louis on highways, during the early morning. I tried to keep speed at 45 in fifth gear, but probably averaged more like 46 or 47 MPH. I didn't use any special hypermiling techniques. This was 1800 RPM, according to my tach. My rear tires are 12", but the fronts are 13" (155/80x13), for 4.5% more gearing. There was little or no breeze when I started and ended the test. Temp was about 60 - 65. I corrected the odometer with 20 miles of mileage markers, which were marked every .2 miles.

Result: for 75 miles, I used 1.2 gallons of gas. This comes to 62.5 MPG. I was very careful to fill the tank completely both times; if anything, I might have put in a couple thimblefuls more the second time.

The moral of this story: low RPMs and less wind resistance really matter. I doubt that the seat removal was much of a factor, if any.

For my next run, I will install a 45,000-volt coil and gap the plugs 10% larger, for a bigger spark. This was successful with a previous Subaru, to the tune of a 10% mileage improvement. I'll drive at 55, like the first test.

Nice. 62mpgs is definitely sweet! I would be curious, and I don't know why it wouldn't, if you would be able to hold those numbers for all, or most of a tank. I suppose the extra weight in gasoline alone might lower it a bit, but I would be curious how much. Nice write up.:headbang:

[spiko]

That's insane, might be a record!

[TominMO]

Did another MPG run today. Took out the rear and passenger seats, folded in the right side mirror. This so I could simulate less gas in the tank, and an L model.

I drove a 75-mile loop around St. Louis on highways, during the early morning. I tried to keep speed at 45 in fifth gear, but probably averaged more like 46 or 47 MPH. I didn't use any special hypermiling techniques. This was 1800 RPM, according to my tach. My rear tires are 12", but the fronts are 13" (155/80x13), for 4.5% more gearing. There was little or no breeze when I started and ended the test. Temp was about 60 - 65. I corrected the odometer with 20 miles of mileage markers, which were marked every .2 miles.

Result: for 75 miles, I used 1.2 gallons of gas. This comes to 62.5 MPG. I was very careful to fill the tank completely both times; if anything, I might have put in a couple thimblefuls more the second time.

The moral of this story: low RPMs and less wind resistance really matter. I doubt that the seat removal was much of a factor, if any.

For my next run, I will install a 45,000-volt coil and gap the plugs 10% larger, for a bigger spark. This was successful with a previous Subaru, to the tune of a 10% mileage improvement. I'll drive at 55, like the first test.