For petrol, diesel and hybrid vehicles it is just a matter of looking at the official combined fuel consumption and your expected mileage over a year, then calculating how much fuel you would expect to use over the course of a year.

For an electric car it is a little more complicated as manufacturers rarely give a consumption figure (although it may be possible to find this if you search around). Instead base it on the expected range from a full battery, and by checking your electricity bill you can calculate what you will have to pay for a full charge.

It is a little bit more complicated than this - both official combined fuel consumption and electric range are best-case scenarios, and the figures you will actually achieve will vary based on the driver and the type of use the vehicle will get - but this should give you a rough idea at least.