If running costs are a key consideration then we would expect the hybrid Toyota to be cheaper than the Ford Kuga, although this does depend on which engines are fitted. However, we would give serious consideration to keeping your current vehicle - you say you are happy with it, it is still relatively new and younger than the Ford despite the higher mileage, while the Toyota's mileage is higher still. If you don't need any more space than the Arona offers you then sticking with your existing car is usually cheaper than selling it and buying something else, even if you are getting them at a good price.