Just fyi, you should be able to get EV at any speed down to around 10
mph or so. I discovered this while driving in the parking lot on the way in to work one morning.
If you want to test it, try the following:
You'll need a long, flat stretch where no one is going to be riding on your tail. Large parking lots can make good candidates. Get the car up to around 20
mph, then let it coast. FCD should go to 100 mpg. Then coax it into EV mode and hold it there (watch out for lamp posts!

). If your experience is like mine, you should see the car slowly decelerate to about 11
mph and stay there. This tells me that, with forward momentum already established, the 20 HP motor can sustain about 11
mph. Not much, and explains why it doesn't do much to hold speed for you while cruising.