mpg vs. speed - Metro graph
 

(Originally written May / 06)

Took a break this afternoon because it was good testing weather ... http://www.gassavers.org/images/smilies/smile.gif

http://images6.theimagehosting.com/m...art.371.th.gif

Bi-directional averaged 1.7 km long runs on my level "test course"

Conditions at SUPN6 as of (3:00 pm EDT) 1900 GMT on 05/03/2006:

Wind Direction (WDIR): NNE ( 30 deg true )
Wind Speed (WSPD): 3 kts
Wind Gust (GST): 4 kts
Atmospheric Pressure (PRES): 29.94 in
Air Temperature (ATMP): 58.8 °F (this temp. avg'd with another land-based station)

raw data fyi:

km/h - W mpg - E mpg
55 ... 83.1 ... 82.4
60 ... 77.8 ... 76.3
65 ... 74.1 ... 71.7
70 ... 71.2 ... 70.8
75 ... 67.2 ... 62.7
80 ... 63.3 ... 59.3
85 ... 59.4 ... 56.4
90 ... 55.4 ... 53.9
95 ... 51.5 ... 50.3
100 ... 46.6 ... 46.9
105 ... 44.9 ... 44.0

This is with the following "mods" in place:

- grille block, wheel skirts, smooth wheel covers, tires @ 48 psi

One thing this confirms to me is that the Blackfly's highway EPA rating is harder to beat compared to other cars i've driven. Meaning, the constant speed at which the car attains its EPA rating is slower than other cars.

I could drive my '89 accord all day at 95 km/h on cruise control and beat its hwy rating by 20-30%.

Same thing with my mom's car. I borrowed it (1997 camry 2.2 automatic) and ran the same road after doing the Blackfly today.

Its EPA highway speed (30 mpg US) is 112 km/h / 75 mph! that's nuts.

FYI - for those who were interested in this thread, I've (finally) posted a summary, with some new cleaned up images, at MetroMPG.com:

• Speed kills: testing MPH vs. MPG in top gear

I like the presentation of the info. Makes it easier for others to see that if you slow down, you use less gas.

Now only if I could get away with driving 40MPH on the Highway. In MN, the lowest allowable speed on the highways is 40mph, but that is asking for serious trouble since most people go about 10MPH above the speed limit.

Example:
55mph limit means go 65
60mph limit means go 70
70mph limit means mash the go pedal till you see God, then slow down a little.

Sounds like Missouri.

Here in California they have a slightly different variation.

50 means go 57 (even as you pass the regional CHP headquarters)
65 means go 70 if you're in a sedan, coupe, minivan or small truck
65 means go 80+ if you're in a 3/4+ ton diesel truck, a Hybrid or a VW bus

65 means go 55 if you're :turtle:

sounds like everywhere i've lived. NO ONE but me:) goes the speed limit or even below. on interstate 95 in richmond they actually call it "The Virginia Autbahn" . But i like the phrase" mash the go pedal till you see God then slow down a little" .:thumbup: May I use it? It's perfect for my coworkers. Thanx. S.:D

Yep, pretty much sounds like Missouri.
Here In IL, the law is,

If it says, ex.55, 60, 40, 45. you can go 5 over without getting pulled over. Once you hit MO, you can go 10-20mph over, even faster if you have a police scrambler and radar detector. Go as fast as Possible without getting shot in East St. Louis, and when the speed limit says 70, go 85 to prevent getting smashed in the rear from a honda going 95. Autobahn Courtesy rules apply :thumbup:

Yup, when I drove from Regina SK to Edmonton AB, that was pretty much the situation... even with snowy weather in the posted 70-mph zone. First I followed a Colbalt that was doing 80mph, then a Corsica that was doing about 82. A huge Ford truck towing a trailer flew by doing around 100, but I couldn't keep up to it. Then I followed another Ford was doing 90 and later an Infinity that was doing the same speed. Finally, the fastest I followed was a buick century that was doing 95 and the Geo barely kept up.

The other interesting thing is that 3/4 of all these fast cars were from Alberta. I guess they can afford to get 7 mpg at those speeds (the Geo gets around 30 mpg).

It's interesting to see just how straight line your plot is MetroMPG. No Excel here, so no graphs but flattish roads have allowed a better idea of my envelope which would be typical of any overweight slushbox with piss poor aerodynamics.

MPG is almost flat between 38 and 50 MPH at around 32 MPG, and it drops sharply below that due to TC slippage if you try and drive steady state.

52 - 31
55 - 30
60 - 28
65 - 25
70 - 21

I take it this was data collected on the great FLA trek of 2007/08?

It's really good data to have.

I wish this type of detail was available from the government agencies (EPA/NRCAN) - in addition to the "city vs. hwy" simulations (which is all they are), I'd like to see an actual plot of fuel economy at various steady state speeds. That, I think, would tell us more in the long run.