This is a tool that calculates the cost of running a car on an annualised and monthly basis, as well as over the specified cost period. In addition, it displays the intermediate, calculated costs that combined give the annualised running cost: the annualised owning cost and the annualised cost of fuel.

For the car owning cost part of the overall calculation, it is necessary to supply the following information:

• The car price.
• The annual cost of finance. If the car purchase is financed by a loan then the cost of finance is the simple interest charged on the loan, specified as a yearly rate. If, on the other hand, the car is paid for in cash, the cost of finance is equivalent to the opportunity cost of capital. This is usually expressed in percentage terms (unless the formatting is explicitly set to express it as a decimal).
• The depreciation of the car value, which can either be entered as the depreciation over the entire cost period or as a yearly rate, and is applied using simple interest. Typically the value of the car depreciates/falls but if it actually appreciates/rises over time, enter a negative depreciation rate here. The depreciation is usually expressed in percentage terms (unless the formatting is explicitly set to express it as a decimal).
• The cost period in years or months.
• The road taxes as a yearly (default), quarterly, or monthly amount.
• The cost of servicing and maintenance as a yearly (default), quarterly, or monthly amount.
• The insurance as a yearly (default), quarterly, or monthly amount.
• The cost of garaging and/or parking as a yearly (default), quarterly, or monthly amount. This amount is defaulted to 0 as it is expected that it is not always a factor in the cost calculation.

For the car fuel cost part of the overall calculation, it is necessary to supply the following information, noting that the values can be given in various units, defaulting to those most relevant for a UK calculation:

• The car usage, which can be specified in units of miles per year or kilometers per year. The default is miles per year as this is the typical unit for a UK fuel cost calculation.
• The fuel usage, which can be specified in units of miles per UK gallon, kilometres per litre or miles per US gallon. The default is miles per UK gallon as this is the typical unit for a UK fuel cost calculation.
• The fuel price, which can be specified in units of pence per litre, euros per litre, dollars per US gallon or currency unit per litre. The default is pence per litre as this is the typical unit for a UK fuel cost calculation. It is important when choosing the fuel price unit to ensure that it is consistent with the currency of the other entered costs, e.g. if the other costs have been given in UK pounds, the fuel price should be specified in pence per litre. When the currency is not UK pounds (pence), euros or US dollars, the fuel price can be given in terms of currency unit per litre.

Associated tool link: http://www.coggit.com/tools/cost_of_running_a_car.html