The vehicle shall also have an automatic transmission.The power plant shall develop less than two gross brake horsepower and be capable of ....The not more than is already clear.......
The wording you have requires interpretation and not knowing the complete situation it is difficult to know what is in the minds of those who wrote it and we must do some of these "common sense" assumptions and hope that these grammar conventions that we rely on are correct in describing what was intended.
To require the transmission for either type motor would require something like this:
"...and having either an electric motor or a gasoline motor. The vehicle shall also have an automatic transmission. The power plant shall develop less than two gross brake horsepower and be capable of ...". The "not more than " is already clear.
I think you are greatly confused. The two points in your discussion are totally irrelevant to each other.
First - we DO NOT KNOW that an electric motors must be rated at twice the expected load for long life. That's totally bogus, and all that will accomplish is to decrease the energy efficiency of the motor. A motor should be able to deliver its full life expectancy if it is loaded at its rating.
Second - the legal rule you cite imposes constraints on what constitutes a 'motorized tricycle' in the jurisdiction where it applies. The rule is intended to limit the power and speed of the motorized tricycle - presumably as a safety concern - and has nothing at all do to with either energy efficiency or the expected life of the motor.
