The weather is hot this week (92F, 80% humidity). Today I drove the car about 25 miles at speeds between 60-75MPH. When I got close to my destination, I noticed I couldn't send any power to the motor when I pushed the accelerator pedal. I down shifted so I could get off & up the exit ramp with some speed. As I pulled away from a stop light, the car was crawling even though I was in first gear with accelerator pedal floored! I barely crawled to my destination a few blocks away.
The issue was the motor controller was getting too hot, and it was self limiting the power to the motor so it didn't cook itself. I let the car sit for a few hours while I was at my event. When I returned to the car, the motor controller was still a bit warm so I put some leftover ice from a cooler on it to cool it down. Then I drove home. I got home just fine while driving high speeds.
I have the Soliton1 setup without any additional cooling. If you live in a warm environment, you should probably consider forced air or liquid cooling or you'll likely suffer a similar situation on a regular basis. Now that it happened to me once, I'm going to look into further cooling, but no promises yet.