Congrats to COZX2 on the 100+ MPG fill!

[MetroMPG]

(Apologies if this is a repeat topic - I've been scarce around GS the last week or so...)

Nice going on the 102 mpg fill up!

http://www.gassavers.org/garage/viewgaslog/239



I'd be lying if I said I wasn't hoping to be the first to cross the 100 mpg barrier (in a gasoline powered non-hybrid) and grant zpiloto one of his 2007 predictions, but I just haven't been using the car enough to beat you to it.

There is some hope for my current tank, according to the SG, but I'm only at around 70 miles or so since the end of May.

I don't mean to diminish the achievement of Serge with his smart fortwo who was the first here to break the 100 mark, but it's worth cheering when one of the regular GS participants does it too.

My hat's off!

[MnFocus]

Woooot Wooot!! and Daaaaang thats like 1300 miles to a tank!???Wowzers!
Gratz gratz Gratz!

[mrmad]

Amazing FE. His gas log shows some substantal gains, and all in the right direction. My question to COZX2 is how much of the improvements he has gained are from aero mods and how much are from driving techniques. For instance, I'm curious what kind of mileage he thinks he would get in level ground at 60mph. Does the car get 60mpg here and the remaining 40mpg are from pulse and glide, EOC cruising, etc?

[CO ZX2]

Originally Posted by mrmad

Amazing FE. His gas log shows some substantal gains, and all in the right direction. My question to COZX2 is how much of the improvements he has gained are from aero mods and how much are from driving techniques. For instance, I'm curious what kind of mileage he thinks he would get in level ground at 60mph. Does the car get 60mpg here and the remaining 40mpg are from pulse and glide, EOC cruising, etc?

Thank you all. I appreciate the comments.

When I joined GasSavers I had just gotten my first 50+ tank. Figured that was a miracle at the time. I owe a lot to the members of GasSavers for their encouragement and ideas. Never dreamed that what has happened could ever be possible.

I had cardboard front end block and rear wheel skirts at that point. I was also engine off neutral coasting on downhills.

I don't drive much on level ground. It's largely upgrade or down, some more severe than others. The downgrades are great and I never thought I could balance the upgrades in to make close to this average.

I have recently observed that I can maintain 75-80 mpg at 65 mph on one of my most level sections. I did remember to check again (same stretch) when on my return trip. Was very close but had some variation during the 4 mile stretch, probably due to slight variations in terrain.

This last tank was all trips to and from my place of business. Even though there is an 1860 ft. elevation drop there are two mountain passes on this trip. Hard pulls. I take advantage of the downgrades to maximize neutral engine off coasting. Then I return home by the same route. Very little coasting in this direction. I have to average 145-160 mpg going because I only average 55-60 mpg on my returns. This recent tank I started before 6 AM to avoid the winds which pick up by 7:30. Unless it's after dark when I come home, I'm almost always battling some wind.

ScanGauge II has helped me immeasurably with my driving. You can see that in my gaslog.

That being said, I have since made significant aero improvements that translated into better FE. I think I have had my driving stabilized enough, long enough, to make this statement. I am very careful to avoid going backward from gains I have made. CO ZX2

[Hockey4mnhs]

eather way amazing!!

[basjoos]

I'm curious how much his driving altitude of 10,000 feet has on the mileage. Driving in air that is about 30% less dense than that at sea level reduces aero drag by 30% and derates (non-turbo) engine power by 30%. He drives at the altitudes that lightplane pilots fly at to get their best FE.

I threw some numbers into a density altitude calculator and, assuming a constant elevation, barometric pressure, and relative humidity, the difference in density altitude between my driving in the winter at 0F and summer driving at 90F is 6409 feet. So the difference between my driving at 1000 feet elevation in upstate SC and my driving at 10,000 feet in the CO Rockies would be greater than my summer versus winter aero drag. I wonder what kind of mileage I could get driving at 65mph at 10,000 feet?.

[CO ZX2]

Originally Posted by basjoos

I'm curious how much his driving altitude of 10,000 feet has on the mileage. Driving in air that is about 30% less dense than that at sea level reduces aero drag by 30% and derates (non-turbo) engine power by 30%. He drives at the altitudes that lightplane pilots fly at to get their best FE.

I threw some numbers into a density altitude calculator and, assuming a constant elevation, barometric pressure, and relative humidity, the difference in density altitude between my driving in the winter at 0F and summer driving at 90F is 6409 feet. So the difference between my driving at 1000 feet elevation in upstate SC and my driving at 10,000 feet in the CO Rockies would be greater than my summer versus winter aero drag. I wonder what kind of mileage I could get driving at 65mph at 10,000 feet?.

Basjoos. Good to hear from you.

When I first joined GasSavers there was this guy in South Carolina posting tanks of 80-90 mpg. His name was Basjoos. Other members felt like his terrain was the place to be, calling it 'Basjoos Country'. I thought 'o man, would I like to be there'. Amazing how things can turn around.

Regarding your calculations, I recently found an aircraft site that cited 14% air drag difference 1000 ft. versus 10,000 ft. I would agree that the power drop is 30-35%. I am not very sure that should be considered an advantage.

Also remember that my 10,000 ft. terrain contains little flat ground. You do well on flat ground but have made comments yourself about how much even slight upgrades kill your mileage. Slight upgrades graduate into major uphills here. One mile straight up to get to Denver, then another mile straight up to get to me. I, too wonder what kind of mileage you could get while TRYING to drive constant 65 mph at 10,000 feet. My car must not have known about the altitude advantage till 6-8 months ago. My best for 4 years had been 43 mpg.

Might be worth the trip. Whatever the results, we could have some fun. Lots of scenery, old homesteads from the mid 1800s, 80s max summer temps, 10% humidity, few mosquitoes and trout fishing.

[basjoos]

Originally Posted by CO ZX2

Regarding your calculations, I recently found an aircraft site that cited 14% air drag difference 1000 ft. versus 10,000 ft. I would agree that the power drop is 30-35%. I am not very sure that should be considered an advantage.

Might be worth the trip. Whatever the results, we could have some fun. Lots of scenery, old homesteads from the mid 1800s, 80s max summer temps, 10% humidity, few mosquitoes and trout fishing.

Yeah, you're right, in comparing 1000ft to 10,000ft, aero drag drops 15% and ICE power drops 32%. But (assuming your ICE adjusts air/fuel ratio to compensate for altitude) that power drop would result in improved ICE efficiency since the ICE is having to operate at a higher throttle setting (less pumping losses) to get the same power output. Your high mileage is a result of your driving skills and aero mods, but the low air pressure driving environment also is a factor. If you were driving an Insight, you'd probably be getting 160mpg.

When they chose Oklahoma to run last summer's Insight marathon, at the time I was thinking that if they had run it on some fairly level, low trafficked roads on the Colorado Plateau in SE CO or southern UT on the plateau at 8000 to 11,000 feet, they could have gotten better mileage that they did in OK.

[omgwtfbyobbq]

Originally Posted by basjoos

But (assuming your ICE adjusts air/fuel ratio to compensate for altitude) that power drop would result in improved ICE efficiency since the ICE is having to operate at a higher throttle setting (less pumping losses) to get the same power output.

I'm pretty sure pumping losses remain consistent at different altitudes because I read that oxygen content is proportional to altitude as well. So, if there's 15% less air density that'll help w/ aerodynamic drag, but pumping losses remain the same because the proportion of air to everything else remains the same.

[mrmad]

Would you have any idea as to the % FE gains on each mod? Hate to ask for all your secrets, but I'd be really interested to know for example which ones were more successful then others. Since I drive in pretty heavy traffic where it would be hazardous to do pulse and glide, or EOC, the fact that you can get 75-80mpg at 65mph in a car rated at 25mpg on level ground is more impressive to me then the 100mpg you are currently getting with driving techniques.