WLPT ranges are useful only in comparing one car with another on a very simplistic basis. As such it's a useful measure. You cannot summarise the efficiency of a car with so many variables using a single value. You need a minimum of a 3D graph showing at least how speed and temperature effect efficiency, but that makes comparing vehicles very difficult for most people. In reality there are probably 10 or more variables including gradient, elevation gain/loss, tyres, tyre pressure, weight as well as those mentioned above that effect range. Therefore WLPT is useful but everyone should be aware of what it does and doesn't mean. Dealers in particular should not be using WLPT range as value for true range when talking to customers.