I developed the attached spreadsheet to help with car purchasing decisions. This spreadsheet works in MS Excel and other spreadsheet programs. To get started download the Budget for a car calculator.
Using the budget for a car calculator, you can play around with the variable costs related to car ownership such as fuel consumption. This allows you to consider the different costs associated with different kinds of vehicles prior to buying one.
For example, comparing two cars, you can consider whether it is better to buy a new car with low fuel consumption but high loan repayments, or a second hand car with higher fuel consumption but low loan repayments.
The kind of perspective a spreadsheet like this can give when making a decision about buying a car could save you a lot of money in the long run.