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You have a 2015 or earlier I assume?I typically do 63mph on almost all highway, I get 33-38 in winter, and 42-47 summer.

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VIN # B0985

So if at 55mph if I get 60 miles range, at 75 I will get only 32 miles range?

VIN # B0985

For gas useage, gearing comes in to play, but the principle is the same. As you speed up, most of the energy is used to combat aerodynamic drag.So if at 55mph if I get 60 miles range, at 75 I will get only 32 miles range?

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According to studies backed by the department of energy, the average car will be at its advertised MPG at 55 mph. But as the speed increases:So if at 55mph if I get 60 miles range, at 75 I will get only 32 miles range?

- 3% less efficient at 60 mph

- 8% less efficient at 65 mph

- 17% less efficient at 70 mph

- 23% less efficient at 75 mph

- 28% less efficient at 80 mph

See the graph below (from fueleconomy.gov):

So in you example, you'd be getting 46 miles of range at 75 mph.

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Those numbers are estimates for *ICE* vehicles, which tend to get better fuel economy in highway driving cycles vs city.According to studies backed by the department of energy, the average car will be at its advertised MPG at 55 mph. But as the speed increases:

- 3% less efficient at 60 mph

- 8% less efficient at 65 mph

- 17% less efficient at 70 mph

- 23% less efficient at 75 mph

- 28% less efficient at 80 mph

See the graph below (from fueleconomy.gov):

So in you example, you'd be getting 46 miles of range at 75 mph.

In contrast, the Volt does better in electric mode in city driving and slower speeds than on the highway. So you would expect the efficiency penalty for high-speed driving in the Volt to be more severe than the numbers given above.

On the other hand, the Volt is more aerodynamic than the average car too. So maybe these 2 factors cancel each other out(?).

Regardless, the general concept still applies. Faster speed = lower efficiency.

I generally try to plan my trips so as to not make driving above 68 a necessity, despite speed limits at 70 plus. I can kep a Gen I at 37 to 41 mpg if I keep the speed down on long trips. I try to hold once on the highway and save the juice for in town but 3 mile per kw is doing good at 68.

I am just not important enough to worry about my trip taking a few extra minutes. and I got XM......

http://ecomodder.com/forum/tool-aero-rolling-resistance.php

Most EVs are not geared for faster than 80 mph efficiency, so drivetrain efficiency might drop at higher speeds, which might not be accounted for by the tool.

This tool will let you model different tires and such, but takes some research to configure appropriately.

PS, I look at watt figure, and for my 2012 I compare it to 9.4 kWh capacity. So if at 80 mph it takes about 26.6 kw to move the Volt, I would estimate my range to be 9.4 kwh/26.6 kw * 80 mi/hr = 28 mile range. At 60 it would be more like 35 miles, and 40 more like 50 miles. This is very close to what I get.

I used 1 kw overhead, .28 Cd, 23.7 sqft area, .013 tire coeff (use 0.01 or less for lrr tires), engine 0.33, drivetrain 0.9, 4000 lbs, rest default. The tool could allow different parameters for different speeds, but it doesn't so you might figure out high speed and low speed models separately.

The cool thing once you have your model setup, you can accurately figure what adding a passenger, changing tires, etc will do to your efficiency.

Highway's are not efficient for EV miles, but getting home quicker is worth it.

http://gm-volt.com/forum/showthread.php?8235-MPGe-at-Various-Speeds/page5

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Parts of my commute, if I choose to use the toll road, are posted at 75mph and I hit 80-85 there. Since the toll road's posted price goes up as congestion on the main roads increases, I generally take the toll road when it is above $5 and get the best bang for my buck. $5 generally gives me back 1/2 hour.

IOW, my decision to DIY (or take a slower route) hinges on: is it saving me more than $20/hour in Psych fees.

And to answer the question, I can use ~6kWh in 5 miles @ 85mph. '14 ELR.

Yes, its a 2014You have a 2015 or earlier I assume?

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2017 volt

More importantly I try not to go over 30kWh at any speed, unless it puts me at too low of a speed for traffic. That seems to help the most. 15kWh and below is a pretty good target to hit on flat surfaces.

Is this in some way surprising that higher speeds reduces range?

The link below had data from a Dynamo which some what supports the below numbers after dividing 14KW-hrs/ (WH/m). ie at 60MPH they had 294 WH/m, 14/.294=47miles

Extrapolating from the link above, assuming 14 usable kWh:

Speed / EV mi EV from Dynamo (added)

30 67 77

35 65

40 63 67

45 61

50 57 55

55 55

60 47 47

65 44

70 42 38

75 35

http://gm-volt.com/forum/showthread.php?246218-60-Plus-miles/page3

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