Mo data on MPH & Octane vs. MPG
With various questions about the Mo's highway MPG and also how octane affects it burning in our minds, I hit the road last night at midnight to do a little testing. First off we found the "test track", nothing more than a relatively flat and nicely repeatable 6.5 mile long section of Hwy 85 here in Silicon Valley, stretching south from Steven's Creek to Winchester for those in the know. While there are some minor elevation changes in the road, it's nothing that makes the Mo's RPMs shift at all on cruise, and we GPS verified that the start and end points of our test track are at the same relative altitude (within 20 feet).
Starting out with 91 octane fuel at 70MPH in the cool 60 degree night air, and then filled up the tank with 87 and ran it again at 70MPH. 23.2 vs 22.3MPG. With the resulting %4 difference, and assuming a $.20 spread from 87 to 91, 87 would have to be *$4.96* a gallon before 91 octane is cheap enough (percentage wise, 91 octane gets cheaper compared to 87 the higher prices go) to warrant buying 91 for the increase in performance. That's not to say that you shouldn't use it anyway in hot weather or when towing, or ocationally to get the detergents in premium fuel to clean out your fuel system, but never get it for improved MPG.
I then also did runs at 50, 60 and 80 MPH to fill in the graph, and then 30, 40, and 50 on surface streets to flesh out the bottom of the graph. Surprisingly the MPG drops off fairly linearly, I expected a much more steep curve because increased RPMs and wind drag should combine to hit hard. Also interesting to see that the tipping point for max MPG is at roughly 40MPH, which basically translates to the maximum speed at minimum RPM.
Here's all the data and graph, enjoy folks:
http://www.zfilms.org/Stories/Murano/2004/6-14/MoMPG.jpg
With various questions about the Mo's highway MPG and also how octane affects it burning in our minds, I hit the road last night at midnight to do a little testing. First off we found the "test track", nothing more than a relatively flat and nicely repeatable 6.5 mile long section of Hwy 85 here in Silicon Valley, stretching south from Steven's Creek to Winchester for those in the know. While there are some minor elevation changes in the road, it's nothing that makes the Mo's RPMs shift at all on cruise, and we GPS verified that the start and end points of our test track are at the same relative altitude (within 20 feet).
Starting out with 91 octane fuel at 70MPH in the cool 60 degree night air, and then filled up the tank with 87 and ran it again at 70MPH. 23.2 vs 22.3MPG. With the resulting %4 difference, and assuming a $.20 spread from 87 to 91, 87 would have to be *$4.96* a gallon before 91 octane is cheap enough (percentage wise, 91 octane gets cheaper compared to 87 the higher prices go) to warrant buying 91 for the increase in performance. That's not to say that you shouldn't use it anyway in hot weather or when towing, or ocationally to get the detergents in premium fuel to clean out your fuel system, but never get it for improved MPG.
I then also did runs at 50, 60 and 80 MPH to fill in the graph, and then 30, 40, and 50 on surface streets to flesh out the bottom of the graph. Surprisingly the MPG drops off fairly linearly, I expected a much more steep curve because increased RPMs and wind drag should combine to hit hard. Also interesting to see that the tipping point for max MPG is at roughly 40MPH, which basically translates to the maximum speed at minimum RPM.
Here's all the data and graph, enjoy folks:
http://www.zfilms.org/Stories/Murano/2004/6-14/MoMPG.jpg