How does highway driving impact your range?

My wife is interested in the i3 (REX) and she'll be doing an extended test drive soon. Meanwhile, I've been doing a lot of research, and this forum has been extremely helpful -- thanks to everyone who posted here!

My wife's commute is about 60 miles round trip, all highway. I know this isn't the best use case for an i3 (and our salesman admitted as much), but it should be possible to make the commute without using the REX, since there are no hills and it doesn't get cold here in South Florida. If you own an i3 and do most of your driving on the highway, how is your battery range (and how fast do you drive)? On my wife's commute, traffic flows at 80 mph on average, so she'll be doing about the same.

Since we would have the REX, we won't have to worry about my wife getting stranded on her way to/from work, but it would be nice to avoid using the REX on a daily basis. There are L2 charging stations at my wife's office, but there's no guarantee that one will be available on any given day, so she would always top off the charge at home.

Related question: At highway speeds, which tends to reduce the battery range more, running the AC or opening the windows?

Of course we'll find out about the range when my wife does her test drive, but I'm curious about the experience of others who might have similar driving patterns.

My commute is 50miles round trip. I charge at work (no L2 charging at home). Mine is BEV. When charge at work, I stop charging at 92%. My round trip will have 26% left. Avg speed is about 30mph. The car is more efficient at stop and go traffic.

I live in Northern CA (Bay Area).

someone in the Tesla forum did a very nice chart on the Rex range and consumption. You may want to check it out.
http://www.teslamotorsclub.com/showthread.php/19331-BMW-i3/page105





Mine is a BEV. I do get better range than listed.

roofless said:

Related question: At highway speeds, which tends to reduce the battery range more, running the AC or opening the windows?

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BMW has said that over 25mph, using the a/c is more efficient than having the windows open. The energy use goes up radically as the speed goes up. At around 56-59mph, the REx can run at max speed and produces the most power, which will almost always be more than you need to keep up if the battery got way down there. At 80mph, you'll be sucking electrons quite fast. The same thing happens with a typical ICE. If your battery SOC gets too low, at 80mph, you might notice the car will start to slow down, but with the latest software, even though you know the route home, you may overcome that issue if you use the nav and put in a route as reportedly, that will allow you to engage the REx earlier to avoid inadvertent slowdowns. WIth it being primarily level is good in some ways (climbing hills at speed is probably your worst power comsumption), but also means less opportunities for regeneration, which, in some situations, can significantly increase your maximum range. The REx uses resistance heating to warm the interior...the BEV uses a heat pump which is much more efficient. The REx should work out for your situation, and the BEV might, but it would be a lot closer.

roofless said:

My wife's commute is about 60 miles round trip, all highway. I know this isn't the best use case for an i3 (and our salesman admitted as much), but it should be possible to make the commute without using the REX, since there are no hills and it doesn't get cold here in South Florida. If you own an i3 and do most of your driving on the highway, how is your battery range (and how fast do you drive)? On my wife's commute, traffic flows at 80 mph on average, so she'll be doing about the same.

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I'm commuting on the highway in Iowa (a lot of hills) and my averages are:
a) 60mph I get average 3.5 m/kWh
b) 70mph I get 3.2 m/kWh
I don't drive faster. I assume at 80 that would go down to about 2.8-3.0
Heater can eat a lot of heat, didn't have a chance to use AC yet.

On average I get between 50 and 60 miles of range with those speeds. I think REx might be great for her. It's would be perfect if she could plug in at work, even using standard L1 (120V 12A) charger. 8h of L1 would give her about 25-30 miles of range, enough to never need the REx.

I drive mostly in Highways at speed of 65miles/H most of the time.
I use to get 120km(80miles) in summer.
Now in winter I get 80Km(50miles).

30miles difference between summer and winter !

Our diesel wagon is more situated for highway-only commutes. I3 DNA is best suited for a metropolis. It's out of its element on highway alone.

Thanks to everyone for the quick and helpful responses.

A little bit of context for my questions: My wife's 3-series lease will end soon, and she's interested in a car that will qualify her to use the HOV lane, which means either a hybrid or EV here in FL (diesels don't qualify). We like BMWs, we like the "green car" concept of the i3, and there are good incentives (including the tax credit), so that's what drew us to the i3 initially, even though it's not a perfect match for my wife's driving patterns. A Tesla Model S would be a much better match, but that (even a used one) is way out of our price range. My wife took a brief test drive in an i3 recently, and liked it well enough, so the next step is to see what it's like to live with one for a few days. If this doesn't work out, we'll probably go the hybrid route.

It will be a couple of weeks before we do the extended test drive, but I'll post an update with the results when it's over.

Look forward to hearing how it goes. I'm sure she'll love it.

If you guys end up in an i3, seriously consider the DC fast charge option. On the East Coast, the SAE Combo infrastructure should be expanding greatly in the coming year and in 2016.

If you guys end up in an i3, seriously consider the DC fast charge option. On the East Coast, the SAE Combo infrastructure should be expanding greatly in the coming year and in 2016.

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I've been told that that most of the 2014 i3's in my area came equipped with the DC charging option. However, it's not a must-have for us, since we won't take the i3 on any long trips, given its range, and we wouldn't keep it for more than 2 years (lease or Owner's Choice), given how fast the technology is evolving. There will be a lot more choices in 2017, including (most likely) a better i3.

kentheteaman said:

I drive mostly in Highways at speed of 65miles/H most of the time.
I use to get 120km(80miles) in summer.
Now in winter I get 80Km(50miles).

30miles difference between summer and winter !

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Is this an I3 with REX? And is this with preconditioning?
I was considering an i3 + REX, but If I only get 50 miles from batteries + same distance from REX in winter (and it is not that cold now in the UK) at 65 mph, I think it really does not suit me. I have no issue driving 65 mph and using ecopro(+), but I woulld have aimed at at least 70m range ...

Driving at 60 mph on UK dual carriageways, I get between 45 and 50 mpg from the rEX, which is 90-100 miles. The range estimation for the petrol range is extremely pessimistic.

PhilH said:

Driving at 60 mph on UK dual carriageways, I get between 45 and 50 mpg from the rEX, which is 90-100 miles. The range estimation for the petrol range is extremely pessimistic.

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I would like to have around 150 km of travel between two refills if I was doing highways. I do not use them very often... I suspect this is in ecopro mode?

roofless said:

I've been told that that most of the 2014 i3's in my area came equipped with the DC charging option. However, it's not a must-have for us, since we won't take the i3 on any long trips, given its range, and we wouldn't keep it for more than 2 years (lease or Owner's Choice), given how fast the technology is evolving. There will be a lot more choices in 2017, including (most likely) a better i3.

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Keep in mind that very few i3 came without DC charging option. To the point that from 2015 MY it's a standard equipment. As such every i3 without it will be treated by market as 'sub-standard' when it comes to resale.

On the other hand, if you lease I wouldn't worry either.

Tomasz, I think resale will be a problem with or without the DC charger, because of future improvements to the i3 and more competitors becoming available (including the Tesla Model 3). I would only consider a lease or Owner's Choice option at this point.

roofless said:

Tomasz, I think resale will be a problem with or without the DC charger, because of future improvements to the i3 and more competitors becoming available (including the Tesla Model 3). I would only consider a lease or Owner's Choice option at this point.

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Look at it this way: how much depreciation is there in a 3 year old smartphone or laptop? An EV is exactly the same at this stage in its development, you would have to be nuts to actually buy one....

WoodlandHills said:

roofless said:

Tomasz, I think resale will be a problem with or without the DC charger, because of future improvements to the i3 and more competitors becoming available (including the Tesla Model 3). I would only consider a lease or Owner's Choice option at this point.

Click to expand...

Look at it this way: how much depreciation is there in a 3 year old smartphone or laptop? An EV is exactly the same at this stage in its development, you would have to be nuts to actually buy one....

Click to expand...

I'm not that sure aboutthis comparison. If technology improves, there will be better new cars coming to the market. But an i3 will still beat any 'standard' car in variable cost, so there will quite some interest in an older one. Look at it as an iPhone, they still go good money second hand

The uncertain i3 future value is what makes leasing or Owner's Choice a good deal. At the end of the term, if the car is worth more than the residual value, you can buy it for the residual, if it's worth less, you can walk away. With Owner's Choice, you also own the car, so you get the full tax credit either way.

After my brief test drive, I arranged with a participating dealer for the 3-day test drive.

I live in the Silicon Valley (Santa Clara, CA). I had planned to drive to SF and back, but plans changed. Having read about the potential issues with steep climbs, I decided to take the vehicle over the Santa Cruz mountains and back. On a single charge I got over the mountains to the ocean; I drove around the area after visiting Santa Cruz. And I made it back to about 3 miles from home before the REx engaged. All in all I believe I got about 75 to 78 miles before the REx kicked in. So I was sold on the i3 REx and now proudly own one.

roofless said:

If you guys end up in an i3, seriously consider the DC fast charge option. On the East Coast, the SAE Combo infrastructure should be expanding greatly in the coming year and in 2016.

Click to expand...

I've been told that that most of the 2014 i3's in my area came equipped with the DC charging option. However, it's not a must-have for us, since we won't take the i3 on any long trips, given its range, and we wouldn't keep it for more than 2 years (lease or Owner's Choice), given how fast the technology is evolving. There will be a lot more choices in 2017, including (most likely) a better i3.

Click to expand...

In that case - bizarrely you'll probably find its cheaper to lease with the DC option even though the purchase cost is higher. They expect the residuals to drop a lot more on cars without rapid charge - because in 2 years from now there will be a demand for it due to increase network availability and cars without it wont sell as easy to second owners.