MPG run, part deux

[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.

[spiko]

That's insane, might be a record!

[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:

[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]

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]

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!

[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]

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]

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

[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.

[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.

[batstiva]

^^ I think in a way, you're both right. I see no real reason why driving more miles, under the same conditions, at the same speed would render different results. But I also think that actually going 200-300 mile would be more like a real world test. I still see no reason why the result should/would be that much different. Course, I also think I might want to shoot myself if I had to drive 45 mph for the 5 or 6 hours it would take to cover that much ground.

[TominMO]

^^ I think in a way, you're both right. I see no real reason why driving more miles, under the same conditions, at the same speed would render different results. But I also think that actually going 200-300 mile would be more like a real world test. I still see no reason why the result should/would be that much different. Course, I also think I might want to shoot myself if I had to drive 45 mph for the 5 or 6 hours it would take to cover that much ground.

I agree, a longer test would seem more definitive. But practically speaking, it was quite hard to go that slow for that long--only 75 miles--on a highway. The main problem was the psychological pressure, when everyone else was driving so fast. I didn't want to be hassling people, or creating a potentially dangerous situation. Quite a number of times I thought about aborting, but hung in there because I said I would do it, and I hate not keeping my word if at all possible.

On a closed course like a racetrack or a very long country road with no stop signs, this would not exist. Plus it was somewhat boring, though on the other hand I did like the relaxation of going so slow; almost meditative.

[TominMO]

I should also point out that during my first mileage run I was not quite as careful in the two fillups, to make sure they were exactly the same. I may have filled it the first time to a little less than the second time. Even a .1 gallon difference would have made a difference of 3 MPG, so possibly I was actually getting as high as 54 MPG. But I'll never know for sure unless I run it again--which I might do.

[batstiva]

I think your best bet is going to be the way you did it this last time. Cram as much gas as you can into it, drive it for however many miles you decide to go, refill it all the way, and calculate from there. I think trying to guess how much is in there, and then try to put that exact amount back in is going to be pretty much impossible. Unless you run it dry, put x amount of gallons in it, and then run it dry again. Still, without using any hypermiler tricks, what you ended up with is pretty impressive.