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How to Hack a BMW i3 For More Driving Range

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European cars have been watered down for the U.S. market for decades. My old 1983 Volkswagen Rabbit GTI had less power and more weight than the Euro-market Golf GTI. The Merkur XR4Ti that the Ford Motor Company sold through Lincoln-Mercury dealerships in the ’80s wasn’t nearly as impressive as its donor car, the European Ford Sierra XR4i.

In the intervening years, however, automobiles have become far more global. Most changes from Euro- to U.S.-spec have to do with arcane differences in government regulations that try to achieve the same thing: make cars and trucks cleaner and safer. There are ways around these differences, whether it means “chipping” a performance car or hacking an electric one.

I wrote about my experiences living with a BMW i3 REx (range extender) earlier this year. After another stint in the same electric German car, I’ve made a few improvements with my laptop computer, a cable, and some free software available on the Internet. The process is called “coding,” and it’s important to note that it could invalidate your warranty, and it could mess up your car if you make a mistake. The specifics of how to do the actual work are best left for a Google search, then proceed at your own risk.

That said, here are the fixes I made to the BMW i3 REx:

Hold State of Charge

On European-spec i3 REx models, you can manually fire up the gasoline engine/generator and maintain the battery level by the iDrive controller whenever the battery’s state of charge is 75 percent or less. This feature allows you to run the slightly noisy twin-cylinder engine on the highway and save most of the electric-only range for the city or for lower-speed driving, where it really pays off. On a standard U.S.-spec i3 REx, the gas engine fires up only when the battery level dips to an indicated 5 percent of charge. After a few computer key strokes, the i3 now has another menu item in the iDrive system that allows activation of the “hold state of charge” mode. You can even store this useful feature into one of the eight presets on the dash to ignite the gas engine at the touch of a button. This change gives owners more flexibility and control of when to burn gasoline to save the battery charge.

Larger Fuel Tank (Yes, you read that correctly)

All global i3 REx models are fitted with the same size fuel tank. The difference is that U.S.-spec cars are programmed to shut down the fuel pump earlier, leaving 1.9 gallons of usable fuel capacity versus the European-spec 2.4-gallon capacity. What’s the big deal with a half-gallon of gas? That extra fuel—actually, 26 percent more—can add 15 to 20 miles of range to the i3. On a primarily electric vehicle, that extra bit of dinosaur juice can be the difference between walking or making it to a battery charger (or a fuel station). The coding process allows you to “enlarge” the fuel tank on U.S. cars. After the alteration, I turned on “hold state of charge” and ran the gasoline engine until it burned up all its fuel. At the next gas station, I pumped 2.39 gallons into the i3 REx.

Auto Door Unlocking

Mercedes-Benz allows you to unlock all the doors when you pull open the driver’s inside handle. In U.S.-spec BMWs, only the driver’s door unlocks when you pull on the handle. What’s the big deal? It’s frustrating to get out of the car and pull an outside door handle only to find a locked passenger door when all you want to do is reach in and grab your briefcase. Recode the locks, and all the doors unlock when you shut off the BMW i3 with the stop/start button. Why BMW doesn’t offer this feature in the U.S. is anyone’s guess. I called a local dealership, and the salesperson told me it can be changed in the iDrive system. It can’t. The only options are coding or living with the annoyance.

Surely you want to know why the U.S-market BMW i3 REx lacks these first two features? You can credit — or blame — the government, specifically, the California Air Resources Board (CARB), which influences such policy well beyond its own state’s borders. CARB classifies the i3 REx as a BEVx (battery extended range electric vehicle), while the Chevrolet Volt, for example, is classified a PHEV (plug-in hybrid vehicle). To achieve that BEVx designation, the BMW i3 REx’s gasoline-powered range must be shorter than its pure-electric mode range, thus the smaller fuel tank capacity. CARB also stipulates that the gasoline engine (the APU, or auxiliary power unit, as the organization calls it) can’t kick in until the battery charge is depleted. So don’t blame BMW for this; blame California. And be thankful that Silicon Valley can help you exploit the necessary loopholes through the magic of coding.