Electric performance cars have several technological advantages over internal combustion engine (ICE) cars. There’s the instant torque, the perfectly flat power band, and the ability to put power down more efficiently. However, one of the biggest advantages of EVs is their ability to torque vector better than any ICE car can dream of and they do it all without differentials. However, BMW is working on an active differential for performance EVs that could make its electric M cars of the future even better.
Could Help With Efficiency
This new design patent unearthed by CarBuzz shows off an interesting new differential technology that sounds unnecessary at first but actually might be worth pursuing. EVs don’t really use differentials for two reasons. If there’s only a single electric motor at an axle, it would require a differential to properly vector torque between the wheels but a differential would reduce efficiency, and therefore range, too much. But with EVs that have two motors at each axle, each motor powers a single wheel, which means they can torque vector far better than even the best ICE cars. So why add a differential?
Even with dual motors at the rear axle, BMW thinks a very unique differential can actually help with efficiency by allowing just one of the motors to power both of the rear wheels at times. According to BMW, using both rear motors all the time to vector torque between the rear wheels is inefficient when full power isn’t needed. So having a differential that can allow one motor to shut down when dual-motor power isn’t needed will help increase efficiency, while also allowing the car to have rear torque vectoring.
It works by using a magnetic coupling and sliding sleeves to engage each motor to power both wheels. So while you’re driving at around 5/6 tenths, the car will still give you the rear-drive dynamics of an M car just with the increased efficiency of using one less motor.
This is an interesting technology that I’m not sure is incredibly necessary, as it’s unclear of just how much more efficient it will be. However, BMW M has always been on the cutting edge of performance technology, so it’s good to see the M Division attempting to invent new technologies for electric vehicles, which are the future of performance cars. There’s no guarantee this technology every makes it to production but it’s an interesting idea that we’re going to be keeping an eye on.