Question:
I have just bought a new car: is it worth me trying to pay it off as soon as possible, by paying double instalments the months I can afford it, or does it not make a difference in the long run? And what's the difference if my interest rate is fixed?

Answer:
If the loan you have is an access loan, then paying double payments will most certainly affect the cost of the loan. This is especially true if you pay in extra money at the beginning of the loan because the more you reduce the capital, the less interest you will pay.

Whether you are on a fixed rate or not, paying off extra capital will reduce your over-all interest costs.