It is important to use the vehicle gross weight c.g. height above datum, H, not the curb weight c.g. height as supplied by your cooperative manufacturer. For the purposes of this discussion, curb weight means empty weight plus fuel and oil but less payload (passengers and cargo). If the vehicle checks out loaded, it will have a just so much improved safety factor, SF, empty. The weight of the fuel can safely be ignored as it is below the center of gravity. The only exception to that is if the loaded vehicle C.G. is very close to the center of the car, in which case the added weight of the fuel may cause handling problems to the the c.g. being displaced rearwards, possibly causing an oversteering problem.
We will use the same data as Case 1 for the example. You were probably wondering why weights of empty vehicle and payload were provided when I said weight did not matter. That's true except for the c.g. calculation. So you will need all four figures to check out a car accurately. Otherwise, you can estimate the c.g. rise in height as 2 to 3 inches for typical passenger cars like wagons.
From inspection of the above diagram, it is apparent that the c.g. shifts rearwards and increases in height. This is true of all vehicles, so maximum performance studies and proving tests should always be performed with a fully loaded vehicle.
Use the chart below to plug in the values taken from the diagram to yield the unknown, that is the LOADED VEHICLE c.g. height, H. All measurements are taken from the surface to the center of the loads. In case Moment, lb.-in. is unfamiliar, it is merely the product of the weight in pounds of the component times the height in inches above the datum (the floor surface).