2019 BMW I3 Unknown Or Other Problems

We were sitting at a traffic light for a few minutes behind another vehicle. Suddenly, our car accelerated very quickly. My foot was on the brake when the car accelerated. I felt the brake pedal depress further as it accelerated. I initially thought a car had hit us from behind and propelled us forward, but there was no car behind us. We were moving as though we had just started a drag race - full acceleration - and the brakes did not respond. We crashed into the car in front of us at full acceleration despite me pumping the brakes at least twice. It was surreal. We drive a 2019 BMW i3. It’s an electric vehicle and I wondered if there was som electrical failure. The car stopped only because of the car we ran into.

The range extender did not turn on while I was driving the car. When the range extender failed to work the car slowed down from 70+ mph to as low as 7 mph in minutes. The car then limped along for several minutes at this dangerously slow speed until the range extender turned on. Once the range extender began working, the car took off like a rocket, going from 7 mph to 70 in seconds. There are no warning lights or indicators in the car that show if the range extender is going to turn on or if it will fail to turn on. This has happened four times while I was driving on a a highway and once while I was driving on a road with heavy traffic. The first instance happened in [XXX] on my ride back from a conference. The car seemed fine for a bit until...