FIRST Horsepower and electric power are interchangable terms. 1 HP = 550 pounds moved one foot in one second. = 746 watts OR a 4 HP motor demands 3 Kw.
SECOND If your driver (gas or diesel engine, electric motor, steam turbine or recip engine, jet engine, water turbine etc etc) can meet the torque demanded by the load then you are OK. It all really comes down to torque.
THIRD Automotive HP are way too high. A 350 HP (Detroit car value) will deliver about 90 to 100 HP to the pavement. A 350 HP truck will drag that car at full throttle and so will a 350 HP electric motor and they won't even break a sweat doing it but the 350 HP gas engine will stall.
FOURTH We Americans demand high HP to let us pass and we just love lots of power. You rarely use full throttle just going down the road. I gotta admit I love having enough power when I stomp on it to get around someone.
FIFTH So the average vehicle needs only about 50 HP to get it down the road assuming a flat road.
SIXTH Now if you want to go hill climbing or you are drag racing or you want to pass at 60 mph then you are going to need more HP thus bigger motor and bigger battery capacity.
