Yes, it was in addition. Just to clarify based on Matt's explanation, would the 40kW value need to be converted into energy units to allow me to add this to the value required to keep the vehicle moving? slightly confused on this part.

Hmm... not sure you're asking the question you think you're asking.

Energy is a quantity, it's an amount. You have an amount of energy you can store in a battery. You have an amount of energy you have to give an object to make it move faster.

Power is the rate at which energy flows, it's how fast you are consuming your energy. Your motor will consume energy at a certain rate, depending on what you are demanding it to do.

Joules and watt-hours are a unit of energy.

Watts are a unit of power.

So 40kW is power, it's the average rate at which you need to be using energy to accelerate, if you want to reach your top speed in 13 seconds (you have 13 seconds to add that much kinetic energy to that mass, so you need to be adding kinetic energy at a certain rate).

The 10.4kW is also power, it's how much power it takes to continue travelling at 60mph.

In terms of peak power, you'd need at least 40+10.4kW = 50.4kW to have a 13 second 0-60 car.

It's actually worse, as Brian pointed out, because you won't be able to actually put 40kW into your motor at first, and then to catch up you'll need to put more than 40kW towards the end of that 13s, but it's at least roughly appreciable.

Then there's inefficiencies and driveline losses. These are the end result of the physics, you waste some energy as heat in the motor and controller and every gear and linkage.

So I presume you were talking about power the whole time. If you were talking about energy then I'm not sure what your question is.