Your monthly payments are a factor you control the most. How well will you negotiate purchase price of the Nismo. I got mine for around $36,800 with no extend warranties etc. Your finance rate is dependent on you as well. Depends on your credit rating, loan terms you chose, finance rate and the down payment. I put $10k down and financed the remainder for 48 months at 4.8%. Total cost of your car,financing, etc over entire term is what you need to look at. It your spreading payments over anything over 48 months you are like spending way to much unless you get an incredible rate from a bank.
I always worry when I see people asking what are your monthly payments. tells me the person isn't prepared to negotiate proper deal with the car dealer. Sort of like a lamb going off to slaughter. It really pays to do research on how to properly negotiate your car purchase and how to get best financing available.
Use google to do some research. With terms like " how to negotiate new car purchase".
10 Steps to Buying a New Car - Edmunds.com