It's not very difficult to calculate yourself on excel. Just open a new excel file and do this:
Write the number of months of loan financing. If you have got an auto loan of let's say 5 years, number of months is 60.
In 2nd cell. input the interest rate, divided by 12 (to get the monthly rate). So if interest rate is 18%, write 0.18/12 = 0.015
In 3rd cell write the value of financing, lets suppose it's 1 million. (Suppose value of car is 2 million and your downpayment is 50% and 50% loan).
In 4th cell, go to Fx (Insert function) on excel, go to Financial functions and then select PMT function. Input rate of 0.015, nper of 60 and PV of 1,000,000. Hit enter and you will get the monthly installment of 25,393 (ignore the negative sign)
Insurance is, as usual, on top of the monthly installment.
If you want to look what will be your monthly installment if you take loan of 800,000 instead or a tenor of 3 years instead of 5, just change the values of the 3 cells and the monthly installment value will automatically change.
P.S. if you can't find the PMT function, just write this in a cell:
=PMT(0.015,60,1000000) and enter. Simple
