AFAIK, you can only claim your actual expenses, like services, fuel (I think), tyres, etc. but not the payment of the loan. Here's what I do: I have an old, white paid off car (2 actually), and I take the monthly tax saving I get and put it into my bond. Then when it's time to pay back, I gladly withdraw and pay the money, as I've had the use of it for a year, interest-free.
Don't get drawn into debt again, except when your vehicle is really giving you problems and you really need a new one. Rather start saving at the 28th of August for your next vechicle.