More BMW i3 Range Extender Details Uncovered

BMW i | April 24th, 2014 by 12
RExExhaust 750x500

BMW has been hosting i3 training events to get their client advisers up to speed and ready to sell the car. I’m very happy to …

BMW has been hosting i3 training events to get their client advisers up to speed and ready to sell the car. I’m very happy to hear they are doing this because I was really beginning to get concerned that they wouldn’t properly prepare their sales staff for this unique vehicle. I even dedicated a post a few months ago to this very topic. I’ve now talked to a few client advisers that have done the training and they reported that they did indeed get a lot of useful information which will help them service their clients.

This week the latest round of training sessions are being held up at BMW headquarters in Woodcliff Lake, NJ and details of what is being taught are starting to leak out from some of the client advisers that are there. A couple things of interest shared were details about the range extender the i3 will offer as an option.

bmw i3 rex 750x651

First, it was learned that the range extender is automatically activated once the state of charge drops below 6.5%. At that moment, it turns on and it’s function is to bring the state of charge back up to 6.5% and to maintain that level of charge. It will not charge the car much above 6.5%, and it will not run if the car is stopped, unless the state of charge is critically low. Therefore you can’t it in a stationary i3 and wait for the state of charge to increase. I knew the automatic turn on point was around 5% to 6%, but now we have an exact level when it engages.

You cannot manually turn the range extender off. This is contrary to what I was told by an i3 product manager at the i3 debut in New York City last July. I remember asking this specific question by saying “What if I knew I’d make it home on electric, say I only had a mile or two to go and the REx was about to turn on, could I just turn it off so it’s doesn’t fire up?” I was told yes, there will be a setting that will allow you to turn it off before it engages, but that setting will reset once you turn the car off. The reason for that is so that the next time you get in the car you won’t forget that you had turned off the REx and you may end up needing it. I would have definitely preferred to be able to turn it off manually, and honestly can’t see why that isn’t going to be allowed.

RExExhaust 750x496

We also found out that the client advisers have been told that while the range extender is in operation the speed of the car will be electronically limited to 70mph. I’m not buying that; I think they were misinformed. I really think there was a miscommunication on this one because I have had conversations with people at BMW that know a lot about this and even very recently they assured me that there isn’t an electronically governed speed limit while the range extender is in operation. I believe the confusion about 70mph is based on the fact that 70mph is basically the top speed that the range extender can comfortably maintain the 6.5% state of charge at while driving on relatively flat ground. The people I’ve talked to in Europe that have i3’s with the range extender say they can drive on the highway at just about 120 km/hr (75mph) and maintain the SOC, but anything higher and the SOC will gradually diminish. It’s my contention that the people running the training sessions either aren’t 100% clear on this, or they really meant for the client advisers to warn the customers that 70mph is really the fastest they should drive at if they need to drive for a long distance. In any event, I believe they got this one wrong and there isn’t an electronic limit, we’ll find out pretty soon since the US i3 launch should be in about two weeks.

I saved the biggest news for last. It was learned that the US version of the i3 REx will have not have a 2.4 gallon gas tank as the European version does. Instead it will have only a 1.9 gallon gas tank. I’m going to pause for a moment to let everybody scream bloody murder now…… I know it’s only half a gallon, but in the case of the i3, that just reduced the gas tank by 21%! For me this is a non-issue, but I know there are a lot of people that will not like this at all. 99% of the time I use the added range of the REx it will likely be for less than 40 miles. Yes, this does reduce the utility of long range trips even more, as you will now probably have to stop for gas every 40 or 50 miles. There was no reasons given for the smaller gas tank but as far as I can imagine, this comes down to one of two things. Since BMW wants needs the i3 REx to qualify as a BEVx and one of the qualifications of the BEVx is that the car has a smaller gasoline range than it does electric range, my thinking is that one of these two things led to the smaller gas tank:


1) The EPA rating for all electric range on the REx came out lower than they believed it would. If they used the 2.4 gallon gas tank, the gas range would be slightly longer than the all electric range, therefore causing it to be disqualified for the BEVx designation. The only simple way to make the gas range less than the electric range was to reduce the gas range by using a smaller gas tank.

2) The EPA rating for the MPG while in range extender mode came out higher than expected, creating the same problem cited above; a longer range in REx mode than in all electric mode. I’ve heard it gets anywhere from 36mpg to 46mpg from people driving REx’s in Europe so this is a possibility. If the range extender got rated at 40mpg, and was using a 2.4 gallon gas tank, then the electric range would need to be 96 miles per charge, which is highly unlikely. If they cut the tank down to 1.9 gallons, then the electric range would only need to be greater than 79 miles per charge, which I believe is attainable, even considering that the REx version will have 6.5% less battery to use than the BEV i3 does, as this is held in reserve as a buffer.

So what do you think? Has any of these new revelations changed you mind about the REx?

Article was first published on bmwi3blogspot


12 responses to “More BMW i3 Range Extender Details Uncovered”

  1. JRobUSC says:

    here’s the most important info about the REx model, and the primary concern most people have who are considering buying an i3 — if you keep on fueling it, it will keep on going. Obviously you would have to refuel every 80-ish miles, but if you wanted to add 1.9 gallons of fuel every 80 miles and drive across the country, you could, without ever actually plugging the car in to charge it.

  2. Freepat 75014 says:

    For me the smaller tank for the US should not change much the usages for this car. Clearly even with European tank it’s only a local commutes Second car EV, the very limited Range Extender only pulling the Range Anxiety in that 2nd car / local commutes only usage (which is not nothing though !), without being large enough to transform it into a full purpose sole-car replacement PHEV that you could go on vacations with. This will make it the most sophisticated small (PH)EV 2nd car limited to local commutes niche maket, and meant to be sold at a Price 3X to 4X thre price of the pure ICE segment leader. I bet an estime success for BMW in that tiny space. Real big BMW “all purpose” Sole-car users like me, see that as a luxury gadget and wont consider it for themselves. X5 eDrive is a lot more interesting for us…. the day BMW will accept to tripple its ridiculous <10KWH battery pack….

  3. Freepat 75014 says:

    Only real bad news in this well documented news is “one of the qualifications of the BEVx is that the car has a smaller gasoline range than it does electric range” . My bet is this non-sense was set to protect TESLA radical full-EV approach that for me is not the optimal in today real world. Personally, I would start by imposing a battery that could cover on one charge per 24h the high average local commutes milleage say more than 50M on full EV, so that # 100% of local commutes that represent 90% of my yearly milleage, can be done in pure electric mode in the big cities. Then the range extender should allow to go on vacations a few times per year with at least 600M total range without that being an issue, so we don’t have to rely on too few fast chargers, expected all saturated when so many people rush to vacation places all in the same time… This for me is a bad regulation that will surely push for 500M nirvana battery arrival faster than possible, but on the other hand will delay EV adoption for real people who can only have one all-purposes car like me. Great for Tesla radicals, bad for the world…

  4. Magendanz says:

    How much for a 2.4g aftermarket fuel tank? And who’s going to be the first person to release a firmware mod that re-enables the European REx features?

  5. Reasoned thought says:

    This breaks this car for me, beyond the price (which was gonna be pushing it) the design means i cannot drive to visit any of the 3 largest cities near me (which have friends and family) this would have been possible with the larger tank and as I rarely go for longer trips using the rang extender in conjunction with the battery would have made those trips possible without a stop for recharging or filling up a 2.4 gallon tank… with its decreased range, the battery only option would be 100% as useful (or useless) so I’m better off with a leaf or more likely a Volt… shame, I would also like to see on this an ability to use it as an emergency generator for my home… but fat chance of that

    • RSR says:

      Why is this so ? The modestly smaller gas tank simply would require somewhat more frequent stops to pump gas (ie every 70-80 miles vs every 100 miles), not a huge inconvenience and since for most of us 90% of trips will be less than 80 miles you will be EV mostly without range anxiety. Forget the Leaf at this time, BEV only and with battery degradation issues and lack of battery cooling its realistic range is likely to be around 65 miles. The Volt is an excellent choice if you typically drive less than 40 miles daily (its EV range is 36-40) and nil range anxiety, but its not so stylish and its GM which for some of us create trust and service issues.

      • Reasoned thought says:

        For the cost the BMW is no longer a better option for me than the Leaf or Volt, both of which are much less expensive. The all electric range for me is too short (just like the leaf) to make the most common road trip for my family (between any of the 3 nearest cities and my home) and the gas range extender would be fine, but I would have to stop twice to refill. I really wanted to like the BMW.

  6. […] BMW launched the i3 REx in the U.S., one of the main difference from the European version of the same car was the fuel tank capacity. […]

  7. […] BMW launched the i3 REx in the U.S., one of the main difference from the European version of the same car was the fuel tank capacity. […]

  8. Stephen Masek says:

    It should not be that hard to install the European gas tank….

  9. […] cars can be charged at 73 fire stations across London but since these are REx models, the range shouldn’t be an issue, should an emergency arrive. According to the first reports […]

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