True costs of a loaded' car? - RaineMan

With the current cost of petrol and the VED changes in the budget everybody is talking about fuel consumption and emissions. These days most cars come with all the extras (PAS, A/C, e/w, etc.) which add weight and increase fuel consumption. Has anyone ever worked out the cost of these on a per annum or lifetime basis? A friend ran a base Ka for many years. She recently changed it for a more recent model with PAS and A/C. After 5,000 miles she finds the newer car does 5 - 7 less mpg. Having ridden in both the new one also seems busier (lower gearing?). She finds the PAS an unnecessary extra. It would appear that besides adding to the purchase price it also adds to the onging running costs.
True costs of a loaded' car? - BazzaBear {P}
If it is lower geared, perhaps that is to blame for the mpg, not the PAS and AC?