U.S. BMW i3 REx Actually Has 2.4 Gallon Gas Tank, But Clever Software Limits Fueling To 1.9 Gallons

FEB 25 2015 BY STAFF 58

When 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. Since BMW 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, and also to meet EPA requirements, the fuel tank capacity was said to be reduced from 2.4 gallons to 1.9 gallons.

This is a 21 percent capacity reduction which translates in a smaller driving range on the range extender itself.

bmw i3 rex 750x651 BMW i3 REx for U.S. has in fact a 2.4 gallons tank

BMW i3 REx Gas Tank Location

*Editor’s Note: This post appears on BMWBLOG.  Check it out here.

Recent developments reveal that the fuel tank capacity of the i3 REx was not physically reduced, but rather controlled via software. This was accomplished by shutting off the fuel pump at 1.9 gallons.

The tech wizards on the BMW i3 Facebook Group have figured out a way to remove the restriction but as always, this is not approved by BMW and might void your warranty, so do it at your own risk.

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58 Comments on "U.S. BMW i3 REx Actually Has 2.4 Gallon Gas Tank, But Clever Software Limits Fueling To 1.9 Gallons"

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Awesome. Now just install an extra tank to increase gas range another 200 miles, and hack the software to turn the Rex on with “mountain mode” and “hold” buttons and you have a real car. It could go on trips and climb grades at safe speeds.

Or you could just buy the much better looking Chevy Volt. Much easier.


The 2016 Volt is great, and I’d probably choose it over the i3 even if they were the same price.

But I really wish the Volt had the i3’s performance.

then drive the Volt in “sport” mode at all times; then you can start complaining about the lack of EV range.

But the Volt doesn’t have a BMW badge!

If I ran out of gas in an i3 Rex and was stranded on the side of the road, it would be infuriating to know that there was still another half-gallon of gas in there that a stupid software hack wouldn’t let me use!

The powers-that-be have deemed that you are not to have any control over your own car, you can just pay for all of it.

People like you and me upset their system because you vote with your feet BEFORE you plunk down $50k.

It’s the iPhone of cars. Imagine if apple made an EV, oh wait…

And the first thing I always do on an Iphone is to jailbreak it.
Without the restrictions it’s a great phone. With them I would never consider an Apple product (and have never own one besides the Iphone).

Yeah, now that we know it is there BMW should enable it on all cars without forcing owners to hack theirs. The artificial limitation is just absurd.

Infuriating. Especially since some of these needless modifications have put people in danger.

+1 ‘Needless’ other than to meet BEVx and CARB standards to sell more potential vehicles and improve BMW’s bottom line. Shameful.

I’m not going to blame BMW. This is a prime example of regulation to the point of absurdity.

This “regulation” is a category that BMW lobbied CARB to create; the “BEVx” category.

Not only does BMW -not- deserve a pass on that, it shows a high level of contempt for their customers.

On the other hand, the BMW i3 was designed to be a BEV. If you simply don’t get the crippled, optional gas range extender, then you don’t need to worry about the idiotic restrictions, nor hacks to get around them, nor violating the warranty with such hacks.

if you really feel that the ability to drive on gasoline for extended driving, the BMW i3 ReX is probably not the car you would want. keep in mind, on most cars, when you hit 2 gallons left in the tank, the “low fuel” light comes on. so whenever the gasoline engine turns on in the BWM i3 ReX, you should *always* consider yourself to be in a low fuel situation.

article quote:
“Since BMW 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, and also to meet EPA requirements,”

Shouldn’t that read CARB requirements????

Yes, the restriction is to meet CARB requirements to receive Zero Emission Vehicle credit for a gasoline burning car.

“But Clever Software Limits Fueling To 1.9 Gallons”

Clever was definitely not the word I was thinking of when artificially limiting the capacity of the gas tank. Maybe clever translates to stupid in Germany…

I’m not on facebook. Could someone explain what one must do to fix the problem.

All it takes is two rubberbands and some paper clips. Send me $100 and I’ll send you the instructions. 😉

There is a process called coding where you can change system software parameters. For example some have changed it to enable a REx hold mode, enable AM radio, Video in motion, in addition to the “larger” gas tank. There are over thirty changes one can make. It is all listed in a document on the i3 Facebook group.

Since it is limited by the fuel pump not the fuel gauge dose that mean it just allows 1.9 G to flow after each petrol stop? So if you put exactly 1.9 G in the empty tank it would register as part full but drive the same distance as is you filled the tank.

I would try 2 things before messing around with the software:

1) fill the tank then run the car until you have used 1.9 G of fuel. Then open and close the fuel cap.
2) do as above but then put something like a broom handle in the fuel hole.

Both of those could potentially trick the car into thinking you have filled up and give you acess to the last 0.5 G.

If either of these work we have a classic car on our hands. Everyone loves the little mechanical tricks that fix things.

2nd thought the tank would need to be part filled. If you have used 0.5 G and the open shut trick resets the counter then you should go from reading 75% on the fuel gauge to reading 100%.

That first sentence is all wrong, should read ” on 2nd thoughts the tank would only need to be part filled”

If BMW only gave us the BEV I3, the world would be a worse place.

Indeed. I wouldn’t even consider the i3 BEV at all. Given the range offered, I might as well get a Leaf. The only thing that makes me consider the i3 is the addition of that Rex.

It would have been great the other way arround a Leaf with a Rex.

And a Leaf + REX with the same “barely crawls up a hill without battery power” limitations that the i3 has would be mercilessly mocked in the press. But BMW and the Cult of the Roundel gets a pass.

The more I learn about the i3, the happier I am that it costs more than I want to spend for my next car.

Drive both of them and you will change your mind.

I wonder about this sentence “Since BMW needs the i3 REx to qualify as a BEVx”

Why do they “need the BEVx” qualification? What benefit does this qualification have over other PHEVs?

Extra CARB ccredits.

I wonder if they’ll regret that move once they consider the impact this has on sales – the handicapped REx performance has led to some pretty terrible PR! One could imagine that the tradeoff of more credits at the risk of decreased sales might not be working in their favour…

It all depends on whether they have incremental profit by producing more units. If they are net subsidy, then the more credits they get per car with lower volume is the way to maximize profits and still hit their compliance targets. However, I don’t think that is the situation with BMW and the i3. There appears to be sufficient demand, so hitting the compliance targets with higher volume and fewer credits per vehicle should be no problem. I think the carmakers are risk averse and the demand was unknown, so they chose this path. I’m sure in retrospect they may wish they had done things differently.

How much are those credits worth? If it’s just software couldn’t they sell the i3 with the optional extra of a larger tank for the cost of a few extra credits?

The ZEV credits don’t have a fixed price, as they can be bought and sold in the open market. Tesla has sold some, and I think they were sold for a couple of thousand for each ZEV credit if I recall correctly.

The worst case scenario, a car maker would have to pay $5,000 dollars for each ZEV credit that they are short each year.

That sets the range between $1 and $5,000, depending on the market.

BEVx is a special category that counts as a ZEV (same as the i3 BEV and Leaf). A PHEV does not count as a ZEV so they can’t use it to satisfy ZEV requirements (which is why the Spark EV was made by GM despite having a Volt).

BMW can sell only the i3 REx and still satisfy their CARB compliance requirements.

The regular i3 meets CARB-ZEV requirements. BMW does not have to produce a gasoline version to meet the requirement… they WANT to produce it (because they determined that’s what sells).

Jake — yes, PHEV’s get ZEV credits, but ZEV credits from PHEV’s can only be used for up to 50% of a company’s ZEV mandate.

The other 50% has to come from selling a pure BEV or BEVx.

First, if you are going to use an RX, do not restrict its use just to get more credits. I think BMW would sell a lot more RX versions if it had more RX range. If the fuel pump is inside the gas tank, you want to not drain it completely because the gas helps to condition the pump, thereby extending the life of the fuel pump. If the fuel pump is outside the gas tank, then it is about the credits and the engineers probably recommend against draining the fuel line completely. JMO

I’ve said this over and over again:

The i3 is a compliance car.

BMW doesn’t want to sell lots of them; they want to sell exactly enough to earn the credits they need to sell their ICE cars, and no more.

I don’t agree with that at all. First of all, the i3 meant an awful lot of work for a mere compliance car. For compliance the easiest route is to just grab an existing model and put an EV drive train in it, like the Ford Focus. The i3 is a 100% independent design. The second point is that the i3 is sold in countries with no EV or clean car credits whatsoever. For example, it is being sold in Brazil, where it is heavily taxed as an imported car. Why would they sell a US compliance car in Brazil? Ford does not sell the Focus there, nor Fiat the 500e, Toyota the RAV4, and so on. The reason is that BWM is aware that there is a new kind of high end buyer who values sustainability. They understand that Tesla has taken a lot of mind share in this space (call it “luxury greens” or something), and that spells trouble if the trend consolidates, which they fully expect. The i program is a response to this reality. It is meant to progress slowly because this is a new space for BMW, but they are cognizant that it exists and… Read more »

Thank you for a well-reasoned and informative response. I learned something.

If the i3 is not a compliance car, why does the entire U.S. fleet of i3 REx cars have the restrictions that are only required for ZEV credits in CA? If they really cared about presenting the best possible product, only the CA version of the i3 REx would be crippled.

It’s a compliance car that doubles as a PR stunt.

Spider-Dan, if you -really- think the BMW i3 is a “compliance car”, then you don’t know what the term means. The i3 is sold internationally; it wasn’t created just be a very limited production car intended to be sold primarily in California.

Furthermore, the European version of the i3 REx isn’t as crippled as the American version.

Now, if you had claimed the American version of the REx option for the i3 makes that particular version of the car, as sold in America, a compliance car… then you would have been correct.

When I say “compliance car,” I mean “a car for which the primary purpose for its existence is not to sell the maximum possible number of units, but to help the manufacturer meet regulatory requirements.”

The fact that the BMW i3 is sold worldwide (and that the Focus EV is sold nationwide) do not necessarily contradict this point. If the primary purpose of the i3 was to generate sales, they would not have crippled the entire U.S. i3 REx fleet to meet a CA requirement.

I would also like to point out that the primary reason that the BEVx gas tank regulation exists is because BMW lobbied for it. What more evidence do you need as to BMW’s priorities?

That being said, I will concede that the Euro-spec i3 REx, not being crippled purely to earn ZEV credits, does not meet my previously stated definition of a compliance vehicle. If that vehicle were for sale in the U.S., I would no longer consider the i3 a compliance car.

But the i3 was not -designed- to be a PHEV. It was designed to be a BEV, and you certainly can buy it that way, here in America just as in Europe. Nor was the REx option on the i3 -designed- to have the crippling restrictions put on it in the American version.

Yes, Spider-Dan, you’re absolutely right about BMW lobbying CARB to create the “BEVx” category, so they could get more carbon credits. But that doesn’t alter the fact that the BMW i3 was not -designed- to be a “BEVx” car. Furthermore, the BEVx category is not a sub-category of the BEV category; that is a type of PHEV. If there is confusion over that, then it appears to me that confusion is intentional on the part of BMW.

Whether the i3 REx was “designed” to be crippled is not something we can know (as we were not involved with the design). But the fact is that BMW lobbied for this regulation prior to the release of the i3, so as far as we know, BMW has never had any intention of releasing a non-crippled i3 REx in the States.

We also know that even though the i3 is sold in more markets than just CARB markets, it was compliance-crippled for the US market. As proven by this artificially shrunken gas tank.

Whether we want to call it a “compliance car” or a “compliance-crippled car” is just a matter of semantics.

The fact that BMW lobbied and negotiated with CARB for the BEVx compliance category doesn’t change that is it a “compliance-crippled car”. It still is, no matter who wrote or wanted the crippling rules that the i3 complies with.

The i3 with 30,000 unit production with worldwide availability is not a compliance vehicle.

Not quite worldwide yet, but that appears to be the intent. Give it a year or two. At any rate certainly way too many countries for a compliance vehicle.

The BMW i3 is a Manufacturing Gamble to save money for BMW. The result has been an advertising budget nightmare.

Every dollar they expected to save with their automated assembly of plastic cars is now being spent to convince the Public that the car is more than a rain-proof plastic golf cart.

Does BMW earn credits for units sold in Michigan? If not, it’s not entirely a compliance car. The i3 was not made exclusively or even mostly for compliance requirements, so I don’t call it a compliance car.

Funny.. I see them heavily advertised and stocked at dealers here in Dallas. Yet Texas has no EV mandate, nothing to comply with. They have no reason to sell them here other than to make money from the car. None of the compliance cars are sold here in Texas. No Prius Plug-in, no Fiat 500e, no Kia Soul EV, etc.

And yet the version of this car sold in Texas is just as crippled as the version configured to meet regulatory requirements (that BMW lobbied for!) in CA.

That explains why I’ve only seen one in Dallas and only one in Silicon Valley during this week. (Saw two Mercedes B-class EDs, a ton of LEAFs, an uncountable number of Teslas, a few Volts, two Focus EVs, and two Fiat 500e. No Spark EVs either.)

Nein! Nein! Nein!

Now if they find that the battery has an extra 20% usable capacity to spare with the car having a true 100-mile EV range and a 100-mile extended range it will be half-decent 😉

So basically all people need to do is modify the software and you’ll get a bigger tank and access to the ‘hold’ mode.

Is it so hard to carry a sealed gallon of tank in the trunk? Jesus people…get a life