Originally Posted by
wphamilton
At 20mph on level ground, to be precise. I agree, it doesn't seem ambiguous
(B) Be incapable of propelling the device at a speed of more than 20 miles per hour on level ground;
That means the motor has to be either too weak to propel one faster, or be fitted with an automatic kill switch (not user controlled) that prevents the motor from operating beyond 20mph. The key word here is incapable, not level ground.