I like to look at these types of calculators to make sure I am considering all the important parameters but I never use them to do the actual calculations. I have found too many that either don't consider all the parameters I want, aren't configurable enough, and some that are simply incorrectly implemented.

One example of this specific calculator is that it compares all vehicles in the same graph, and all vehicles use the same parameters. However, not every vehicle actually has the same parameters. For example, the resell value of different brands varies significantly. The maintenance cost of different brands varies significantly. I don't want to be too harsh on this because it does provide some value and seems to be implemented by a well meaning student. I just would never suggest someone use it to actual compare the cost of ownership of different vehicles.

EDIT: Another thing that's hard to model is road trips. During which time gas prices fluctuate and electricity prices shot up.