27 Months & 56,000 Miles: 15,000 kWh of Electricity & 50 Gallons of Gas

Over the course of 56,000 miles, I've driven on pure battery 96% of the time.

My 2014 BMW i3 REx is now 27 months old, and the mileage on the odometer just recently surpassed 56,000 miles. I've needed a little over 15,000 kWh of electricity, and exactly 50 gallons of gas to power the vehicle thus far. That means I've driven on pure battery about 96% of the time, and managed an impressive overall gasoline consumption of 1,120 mpg.

Normally I wouldn't highlight the gasoline use in my electric car; it's really not something most electric vehicle owners like to do. However, as many Chevrolet Volt owners can attest to, adding a range extender to a short range (under 100 mile AER) electric vehicle can expand its versatility immensely. While I haven't needed to use the REx often, there were plenty of times, especially in the winter, that I was very happy it was there.

Back in early 2014, a few months before the North American i3 launch, I openly debated whether I'd buy the BEV or the i3 REx. I ultimately decided on getting the range extender, because the EPA range rating wasn't as high as I had previously hoped. If the i3 BEV had an all electric range of 95 miles per charge or higher, I would have opted for the BEV. The EPA rating of 81 miles per charge just wouldn't be enough for my high mileage driving needs, and even though I had lived the past five years with two pure BEVs - the MINI-E and ActiveE, I chose to go back to gas with the i3 REx.

The vast majority of energy used to power my i3 was generated by the 9kW solar array on the roof of my home.

However I have to admit, I thought I'd need to use the range extended more than I actually have.  Of my 56,000+ miles, only 1,925 miles have been with the range extender running. I've bought 50 gallons of gas (I kept records) and averaged 38 miles per gallon while the range extender was running, just slightly less than the EPA rating of 39 mpg.

But just how little gas is that? Well, as I've said I've owned the car for 27 months now, so that averages out to me needing to refill the tiny 1.9 gallon gas tank about once every month - I drink more coffee than that in a month! However, refueling hasn't been nearly that regular. I've gone stretches of four or five months at a time without needing to buy gas. But I've also taken the car on a couple road trips of two or three hundred miles where I needed to refuel three or four times in the same day to complete the journey. In fact, the majority of my REx miles were accumulated on long trips. These trips simply wouldn't have been possible in an i3 BEV, as charging infrastructure is only now becoming available along the routes I've traveled.

My lawn maintenance contractor cutting the front lawn

To put the tiny amount of gas my i3 needed for the past 27 months into perspective, more gas is used in a year to mow my lawn. I have a large lot, it's a little over two acres and most of it is grass. So I asked my lawn maintenance contractor how much gasoline he needs to mow the lawn and he told me about a gallon and a half. Our lawn gets cut between 32 and 36 times a mowing season including Fall clean-ups, and that adds up to about 50 gallons of gas. I've spent about $145 on gasoline, but since I have solar it's difficult to assess exactly how much the electricity cost me. To simplify things I'll just assume I was paying market rate for the approximate 15,000 kWh I've needed. I'm currently paying about 11 cents per kWh, so that's $1,650 for the electric. Therefore, even if I had paid market rate for all my electric, the total cost to power my car 56,000 is $1,795, or $.03 per mile. I'm sure if I could factor in the exact solar discount, I'd be closer to about $.015 per mile which is pretty incredible.

I can now look back on the decision to get the range extender and confidently say it was the right choice. I probably could have managed with the BEV if the climate here in New Jersey was more like Southern California, but along with the harsh winter weather comes reduced range. From December through February, I averaged only about 55 to 60 miles per charge, down from the 70 to 75 I can rely on during the rest of the year. If only the BEV i3 offered the 95 or so miles of electric range I had hoped, then it would have adequately served all of my needs outside of the occasional long distance trip. In which case we would have just used my wife's car for the long trips instead. In fact, if I didn't have the range extender, there would have been many days where I took my wife's car, just in case. Most of these days I never needed to fire up the REx, but having it there allowed me to use the car that day and not worry about rearranging my day to find a place to plug in. I'm sure if I had bought a BEV i3, it wouldn't have 56,000 miles on it already.

The harsh winters of New Jersey meant opportunity charging whenever possible, as well as more use of the REx.

The good news is the 2017 i3 is getting a battery upgrade, and the range for the all electric BEV i3 will increase from 81 miles per charge to 114 miles per charge.  That's an impressive 40% increase in range without increasing the physical size of the battery. The new battery is simply better, and more energy dense. The i3's battery pack is comprised of 96 battery cells, packed 12  cells per module, with 8 individual modules. Each cell now holds 94 Amp-hour (94 Ah) of electricity, up from the 60 Ah cells used in the 2014 through 2016 i3s. The 2017 models will be available in the US within a few weeks, and I've already heard reports from new owners in Europe where they driven as far as 130 to 150 miles on a single charge with the new, improved battery.

The intense competition within the industry is creating improvement in battery technology faster than ever before.

Battery improvements and increased electric range is happening across the industry. The 2011 Nissan LEAF had an EPA range rating of 73 miles per charge. The 2016 LEAF now has a 107 mile rating and by next year it's rumored to jump up to approximately 200 miles. By the end of the year Chevrolet is introducing the all electric Bolt EV which will have a 200+ mile range and replace their current all electric offering, the Spark EV which has an 82 mile range. The 2016 Volt now has 50% more electric range than the 2012 model did. Sometime in late 2017, Tesla is scheduled to launch the 2018 Model 3, their affordable 200-mile electric sedan. However even with longer ranges, increasing the public infrastructure will be key in gaining market share, especially in the more rural areas of the country.

Before long, 200 miles of electric range will be the norm, and BMW will have to up the ante again. They know that, and their battery supplier, Samsung SDI is already far along in development of the next battery which will undoubtedly end up in future i3s. That being the 125 Ah cell which is not only much more energy dense than the current 94 Ah cells, but it's also smaller and lighter. As EV ranges increase, and public charging infrastructure continues to mature, they'll be less and less of a need to bother with the added complexity of a range extender. Sounds good to me, we're just not quite there yet in my opinion. Extended range electric vehicles like the Volt and i3 REx are still a good choice for many who want to transition from gas to electric drive. There's no magic bullet, the more options available, the healthier the plug in electric vehicle market will be. 

462 Mile REx Road Trip: New Jersey to Vermont

Perhaps the most discussed topic of the BMW i3 is the implementation of the range extender for the North American market. In an effort to have the vehicle qualify for the California Air Resource Board BMW set restrictions on how and when the range extender can turn on, effectively reducing the utility of the REx. These restrictions are most apparent when attempting to use the car for long journeys which include drastic increases in elevation.

This topic has been covered here and on every other EV site extensively, and recently it was announced that BMW is working on a software update that will allow, under certain conditions,  the range extender to come on much earlier than the 6.5% threshold it currently uses. I am actually beta testing that software for BMW now, having had it installed on my i3 just last week. The new software also includes some other updates that will be standard on 2015 i3s and will be uploaded to current i3 owners sometime early next year.

However this post will detail a New Jersey to Vermont road trip that I took a few weeks ago, just before I had the new software update. My in-laws live in Vermont, and I had been wanting to take this trip with the i3 ever since I got it, but I just haven't had the time. Once I knew I would be getting the new i3 software which would be adjusting how the range extender would work, I knew I needed to make the journey before I had it done, so I could perhaps compare the difference in performance the next time I go.

The Active Cruise Control is awesome. I don't think I'll buy another car that doesn't have it. 

I have taken the car on a few 200+ mile round trips, having the ability to charge up before heading home, but this would be much further, about 250 miles there and about 210 miles back home. The trip there would be longer because we were meeting at a restaurant farther into Vermont before heading back to the house. A couple of years ago I installed a Clipper Creek CS-40 at my in-laws' house, knowing that the day would eventually come when I drove an EV there, but I had never used it until now. My previous EVs (MINI-E and ActiveE) would have just been too much of a hassle to try to make this long of a trip, but the range extender is perfect for an occasional trip like this - or at least I hoped it would be.

Most of the roads in Vermont were covered in ice and snow. My new Blizzak snow tires performed very well and I definitely recommend them for i3 owners who need to drive in the snow.

The truth is, I really didn't know if such a long trip at highway speeds, which would include an overall elevation gain of nearly 1,000 feet would be doable without the car going into the dreaded reduced-power mode, where the vehicle slows down for a while so the REx can replenish the battery a bit. Also, in the final 50 miles of the journey I needed to climb 500 feet before descending 500 feet and then climb about 700 feet to our destination.

My wife and I set out early on a brisk morning with the temperature being only 15 degrees when we left. I didn't precondition the battery or cabin, and the total weight we were carrying was about 450 lbs between me, my wife and the items we were bringing up to her parents'. I topped off the gas tank the night before and left fully charged. The trip is nearly all highway and my plan was to set the cruise control for varying speeds between 70 mph and 75 mph to see how fast we could go with the REx maintaining the state of charge. I would drive the whole way there in Comfort mode and possibly use Eco Pro for the return trip.

A few blocks from our destination we came across some cows.

The combination of the very low temperatures, using the heated seats, cabin heat and  driving 75 mph meant the range extender turned on after only 48 miles. That's the earliest I had ever seen it turn on before. I had barely made it to the New York State border and I was already running on gas. So now I had a little over 200 miles to go and it would be all done on the range extender. I figured I'd need to stop three times so we searched the GPS for gas stations that were directly along the route and at the intervals we needed. I wanted to stop when we had about 10 miles of range left and we were able to pretty much get close to that on all three stops.

I needed to stop three times to fill up on the way there.

We made the first stop right about at the 100 mile mark which was about two hours into the journey. My wife laughed at how quickly the tiny gas tank filled up and we came up with the idea that she would time me on future stops to see how long it took to fill up. She would use the stopwatch app on her phone and we would start it when we exited the highway and stop it when we were back on the highway to see just how long the diversion was. We averaged a little over 2 minutes per stop and the best time was one minute, forty eight seconds. All three stops added a total of about seven minutes to the trip - not exactly much of an inconvenience.

The car looked like I was off-roading all day when we arrived. I finally got to test out the EVSE I installed at my in-laws' house over two years ago. Thankfully it worked.

For most of the trip I had the Active Cruise Control set to 70 mph, but I also spent some time with it set to 73 mph and 75 mph. As I expected, 70 mph seemed to be the sweet spot for holding the SOC. Even with inclines that lasted for a mile or two the car never went into reduced power mode. When I set it to the higher speeds it could maintain the SOC on flat ground, but the inclines had the SOC bar graph getting dangerously close to completely evaporating so I kept it at 70 whenever I was going up any kind of hill. One thing I can say, the Active Cruise Control really rocks for long drives like this. It holds the speed, slows down when the vehicle ahead reduces its speed and maintains a nice safe distance. I used it for virtually the entire trip and it is definitely worth the cost if you do a lot of highway driving.

We arrived after nearly 255 miles. About 207 of those miles was done using the range extender.

So, we made it without ever going into reduced power mode. I guess there is no need to do a comparison trip with the new software since this trip went flawlessly. The only thing I can think of doing is possibly trying the same trip with the ACC set to 75 mph the whole way to see if the new higher REx buffer allows me to maintain the faster speed. As it is now though, 70 mph is definitely the magic number for long distance REx driving. If most of the trip is on relatively flat terrain, the SOC buffer is big enough for sudden bursts of speed for passing and to sustain climbs for a few minutes and a couple of miles. Even though it worked out fine for me, I'm happy that BMW is increasing the battery buffer so longer, sustained mountain climbing will be possible without going into reduced power. I haven't had enough time with the new software to really comment on how well it works yet but I'll do that soon.

The final stats for the trip

The trip home the next day was pretty uneventful. I did precondition this time and drove the first half of the way in Eco Pro mode. It was also about ten degrees warmer. All that combined to allow us to go 15 more miles on battery than we had the day before, giving us a total of 63 miles before the range extender turned on. We arrived home with 462 miles on the trip odometer and an average consumption of 3.4 miles per kWh. I filled up with gas about 1.5 miles from my house so we left and arrived with a full tank. Including the final stop to top off we made seven stops for gas (3 going and 4 returning) and bought a total of 9.87 gallons of gas. We drove 111 miles on battery and 351 miles with the range extender running and averaged 35.5 miles per gallon. That's a little less than what I usually average for the REx, but this was a continuous 70 mph for the vast majority of both legs of the trip so I expected it to be lower than usual. If we had taken our other family car like we usually do for our Vermont trips, we would have needed 19 or 20 gallons of gas or about double what the i3 needed.

Getting ready to leave for the return trip back to NJ

In conclusion, these kinds of journeys are definitely not what the i3 REx was really developed for. The tiny 650cc motorcycle engine isn't really engineered to operate for hundreds of miles at a time and I'm sure if it was subjected to this kind of use every week it would certainly have premature mechanical issues. However using it as I do, for the occasional 10 or 20 miles here and there, or the final 3 miles on some days just to make it home plus a road trip every month or two, it's really a great alternative to spending an additional $20,000 for a battery that's triple the size of the i3's. The range extender model is a good stop-gap measure until there is a decent DC fast charge infrastructure in place, which is really the ultimate goal. BMW has some very good news with regards to DC fast charge infrastructure that they will be announcing very soon, perhaps even at NAIAS in January. They are making a significant investment in this area and I believe the EV faithful will be very happy when the news is announced.