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The numbers have to be taken in context. Low temperature kills range. So does high speeds.

Bolt EV is EPA rated at 238 miles (383 kms) combined. Highway rating is 217 miles (I believe EPA uses 60 mph as highway speed). The speeds in this report are 20 mph above that. Bolt EV has a relatively higher CD (.3 vs .2x for other BEVs), which makes it more utilitarian but less efficient at highway speeds, especially at 80mph.
 

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What is the sweet spot for highway speed that does not kill range? Do you also know CD for volt gen1?
 

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What is the sweet spot for highway speed that does not kill range? Do you also know CD for volt gen1?
The crossover between static loads and aero loads where the vehicle has the least energy required occurs somewhere around 20 mph for a modern car without big HVAC loads. EV efficiency is sufficiently even that this is likely the longest range speed to drive at, too.

Obviously only the truly dedicated drive that way, so for the rest of us it becomes a balance between efficient enough to be happy/get there and fast enough to be happy.

The other way to look at it is the Bolt charges at about 180 mph on a good CCS charger in the bottom half of the pack, so driving faster and getting to the charger sooner will yield a shorter overall trip for pretty much any legal speed, provided the trip is long enough to need charging and suitable chargers are available where you need them.
 

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Cd for the Gen 1 Volt is 0.28. I have found the "sweet spot" for the Volt (unless you are trying to hyper-mile) is in the 40-50 mph range. Aero drag force varies with the square of the speed and power varies with the cube, so going from 50 mph to 70 mph doubles the drag force and the drag power almost triples. 80 mph is an absolute range killer.

FYI, 0.28 is an excellent drag coefficient and the Bolt's 0.31 Cd also is very good, compared to almost any ICE vehicle. For example, the sporty and sleek Mazda RX-7 has a 0.31 Cd. Tesla gets all the rave with the 0.23-0.24 Cd range, but it isn't that much of a factor in annual overall driving range, as Cd really only makes a difference at highway speeds. Most daily driving for most drivers, except for long-distance commuters, is 50 mph or less.

Also note the the Cd is only one-half of the equation of body geometry affecting drag. The other half is the frontal area ":A". Total drag factor is Cd x A, expressed in square feet or square meters. Frontal area for more roomy vehicles with more head room will necessarily be larger.

https://en.wikipedia.org/wiki/Automobile_drag_coefficient
 

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Notice that the Bolt has the highest battery capacity of any vehicle in that group. That means more battery weight. Heavier = more energy required to move it.

The Hyundai IONIQ Electric is a much smaller, lighter, more streamlined vehicle with a smaller battery and much less range. It has a better efficiency number, but those are the real world trade-offs. Not surprising.
 

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The Bolt has more range, much better acceleration, and weighs in at ~400lb more.
It probably has better handling as well.
It has a higher driver's seat and roomy back seats.

A Volt is quicker than the Hyundai as well.

Driving 'green' no longer has to suck.

And with only 353 IONIQ EVs sold since March, the odds of actually getting one are slim.
 

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My Gen I Volt does its best time vs. efficiency at around 45 mph. We have parkways near me with 40 mph limits and I can do as much as 6 miles per kWh at 45 mph, usually around 5 miles though with HVAC on fan 3 or Eco 2. I haven't done a highway run for a while, but if memory serves, I get around 4.2-4.4 at 63 mph, then it goes down hill efficiency wise. As I go over 65 mph it is dropping under 4 miles per kWh.


Cd for the Gen 1 Volt is 0.28. I have found the "sweet spot" for the Volt (unless you are trying to hyper-mile) is in the 40-50 mph range. Aero drag force varies with the square of the speed and power varies with the cube, so going from 50 mph to 70 mph doubles the drag force and the drag power almost triples. 80 mph is an absolute range killer.

FYI, 0.28 is an excellent drag coefficient and the Bolt's 0.31 Cd also is very good, compared to almost any ICE vehicle. For example, the sporty and sleek Mazda RX-7 has a 0.31 Cd. Tesla gets all the rave with the 0.23-0.24 Cd range, but it isn't that much of a factor in annual overall driving range, as Cd really only makes a difference at highway speeds. Most daily driving for most drivers, except for long-distance commuters, is 50 mph or less.

Also note the the Cd is only one-half of the equation of body geometry affecting drag. The other half is the frontal area ":A". Total drag factor is Cd x A, expressed in square feet or square meters. Frontal area for more roomy vehicles with more head room will necessarily be larger.

https://en.wikipedia.org/wiki/Automobile_drag_coefficient
 

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Wind loading really affects efficiency. With the help of a strong tailwind you can bump up your cruise speed from, say, 65 to 75 without using much more fuel. Alas, there is also headwind.......
 

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That's pretty remarkable.

The EPA ratings have the Ioniq only 11% more efficient than the Bolt, but this test showed a 34% advantage for the Ioniq.

I wonder how much of this was due to the Ioniq's heat pump vs the Bolt's lack of one.

Aero is another suspect for explaining the discrepancy, but only 30% of the driven route was highway.
 

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Yeah, at 5C I imagine it is the heater in the Bolt EV. It is ok to measure heater use, but you really have to be careful since you need to measure heater performance to understand its expected performance impact. Was the Bolt EV warmer in the cabin?
 

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Cd for the Gen 1 Volt is 0.28. I have found the "sweet spot" for the Volt (unless you are trying to hyper-mile) is in the 40-50 mph range.
Ari will probably disagree with your sweet spot. And unless you can post 80+ miles in a Gen 1 car, I'm gonna believe his number of 23-24 MPH being the sweet spot.
 

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Imagine Ioniq's range with 60kWh batteries....
Imagine the Bolt EV's range with a 160 kWh battery. If we're imagining why not go for 250 kWh?

Ari will probably disagree with your sweet spot. And unless you can post 80+ miles in a Gen 1 car, I'm gonna believe his number of 23-24 MPH being the sweet spot.
IIRC GM has said the greatest efficiency for a Volt was achieved at 28 MPH. It was a while ago so it might have been 38 MPH -- definitely an "8" preceded by a "3" or, more likely, a "2".

Bolt EV has a relatively higher CD (.3 vs .2x for other BEVs), which makes it more utilitarian but less efficient at highway speeds, especially at 80mph.
The CD is vastly over rated. Drive train efficiencies make a big difference as do other factors. Using the heater can make a bigger difference than CD, which I'm guessing is the case here.
 

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Imagine the Bolt EV's range with a 160 kWh battery. If we're imagining why not go for 250 kWh?

IIRC GM has said the greatest efficiency for a Volt was achieved at 28 MPH. It was a while ago so it might have been 38 MPH -- definitely an "8" preceded by a "3" or, more likely, a "2".

The CD is vastly over rated. Drive train efficiencies make a big difference as do other factors. Using the heater can make a bigger difference than CD, which I'm guessing is the case here.
Engine on, or engine off? I'd be shocked if the most efficient speed in EV driving is over 30 mph without HVAC use, and 18 is more likely than 28.

Due to the design decisions in the first generation Volt architecture, I could easily see 38 being cited as the most efficient speed in extended range mode, since the engine isn't tied to the wheels until you hit 36 mph. The efficiency loss of the double conversion will be much higher than the overall loss increase going from 20-40 mph.
 

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Efficiency is less important for folks who put a premium on the car's internal volume, which the Bolt has in spades. Couple the utilitarian design and it's best-in-class range and the Bolt simply rules. I hope to charge on the sun's dime in the near future so that makes efficiency irrelevant.
 

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Anyone who has lived through a cold winter knows heater use (especially resistance heating) dwarfs other factors regarding range (the only real measure that matters imo).
 

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Anyone who has lived through a cold winter knows heater use (especially resistance heating) dwarfs other factors regarding range (the only real measure that matters imo).
My wife drives our Bolt. I asked her about how the heater is affecting the battery range, as I posted in another thread was, "Who the hell cares? (laughing) I don't pay attention to gas stations or battery range anymore. I always arrive home with at least 90 miles to spare."

So there you have my scientific poll results, on how the resistance heater affects the Bolt's winter range :)

By the way, if you want to see the high efficiency heater the Bolt uses check out http://gm-volt.com/forum/showthread...ve-element-or-heat-pump&p=4356689#post4356689
 

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My wife drives our Bolt. I asked her about how the heater is affecting the battery range, as I posted in another thread was, "Who the hell cares? (laughing) I don't pay attention to gas stations or battery range anymore. I always arrive home with at least 90 miles to spare."

So there you have my scientific poll results, on how the resistance heater affects the Bolt's winter range :)

By the way, if you want to see the high efficiency heater the Bolt uses check out http://gm-volt.com/forum/showthread...ve-element-or-heat-pump&p=4356689#post4356689
Yup, once you get rated ranges in the 200 mile range, any sort of around town driving is basically a non issue, having a small affect on your monthly electric bill but not much else.
 

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For around town the range of the bolt makes the reduction in range due to cold a non issue. We had our first real cold day yesterday and I ended up about 2.5 miles/kWh for the day. Today I had the lowest range on the guessometer after a hill top reserve charge (145). Even with those low ranges I can easily do my daily drive which was about 70 miles yesterday.
This is why I think it's important to not talk range and talk battery size to get ev's accepted by the general user. People will be pissed if they buy a car expecting 230 mile range and suddenly it's 120-140 due to weather. Also you can't expect everyone to not use heat for more range. People want comfort.
 
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