BMW i3 REx can be hacked to have 2.4 gallons

BMW i | September 3rd, 2015 by 5
bmw i3 rex underbody 17 750x500

So it’s official, the United States has some very odd automotive restrictions that are making our lives worse. Maybe that’s a bit of a stretch, …

So it’s official, the United States has some very odd automotive restrictions that are making our lives worse. Maybe that’s a bit of a stretch, to say that our lives are worse, but some these incredibly strict U.S. restrictions are doing more harm than good. One example is that for a vehicle sold in the United States to be named a BEV (Battery Electric Vehicle), it must have a smaller gasoline range than electric range. This restriction put BMW in a bit of a pickle with the i3.

bmw i3 bev rex comparison 750x265

See, in Europe, the BMW i3 REx’s (Range Extender, which has a gasoline-powered generator to help charge the batteries) fuel tank can hold 2.4 gallons. The 2.4 gallons of fuel would give the BMW i3 REx a longer gasoline range than its batteries would alone, meaning that the i3 REx could not be sold in the ‘States as a BEV. Forget that the i3 puts only electric power to the wheels and the gasoline engine is nothing more than a generator for electricity, but because it has a bigger gas tank than electric range, it’s not a BEV, according to the United States. Stupid.

bmw i3 rex underbody 18 750x562

But as a work-around, BMW decided to limit the North American model’s fuel take to 1.9 liters, effectively lowering the gasoline range to under the battery’s. However, BMW did this using a software tweak, making the fuel pump cut off at 1.9 liters. This was smart, by BMW, as now it didn’t have to go through the trouble of creating a new fuel tank just for the North American market.

Well, some clever BMW i3 REx owners learned of this software tweak, and the absurdity behind its necessity, and decided to do something about it. A small software hack was created for the BMW i3, essentially unlocking the extra half gallon of fuel in the tank. While a half of a gallon may not seem like a lot for a regular car, it’s quite a bit for a car with a 1.9 gallon fuel tank. After this simple hack, i3 REx owners now have an even further total range. But that’s not the only benefit. In Europe, the BMW i3 REx has certain functions which utilize the extra fuel in the tank to conserve battery during heavy loads, like going uphill. These can also be unlocked.

However, there is some risk in utilizing these hacks. Doing so will void the warranty on your i3 REx, even though you’re just unlocking potential that is mechanically there and utilized in other markets. Don’t blame BMW, blame ridiculous U.S. restrictions. So if you absolutely need that extra half gallon in your REx, there’s a way to get it. But do so at your own risk, as your warranty will be void.

5 responses to “BMW i3 REx can be hacked to have 2.4 gallons”

  1. Nicholas Kosior says:

    Or, you could save the settings before you code the car, then you could load those settings before you take the car in to BMW.

    Also, you could save your changed settings so that after your service you can reload your changes.

    You can also code the Rolls Royce gong noise, auto mirror fold with door lock and get rid of that silly accept button for the iDrive.

    I’m just guessing, no actual knowledge or experience.. I assume it’s very difficult and only the most knowledgable hackers could do it… It really couldn’t be that easy, could it?

  2. JStenq says:

    The Magnuson-Moss Warranty Act has something to say about manufacturers voiding warranties when the hack has nothing to do with problems covered under the warranty… Talk to a lawyer, but BMW may have to prove that the hack itself caused the problem to not cover a repair. Warranties on the batteries, brakes, A/C, radiator, etc… have nothing to do with the hack and should still be covered.

  3. Tom says:

    Pretty neat hack. Good on you, programmers!

  4. R3D says:

    “BMW decided to limit the North American model’s fuel take to 1.9 liters”
    “making the fuel pump cut off at 1.9 liters”

    You mean 1.9 gallons, right?

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