Maybe, someone could parlay their car buying experience with me. My
mother is in the market for a new car. We went to the dealership to
browse cars and the salesman begins his routine. We were in the
initial stages of the car buying process (she wanted to see if she
looked good in the car. Really!) The salesman put us on the fast
track. He even offers to approach the sales manager for incentives.
The car in question is in extreme demand and the dealers only sell
them at MSRP. In addition, the cars are often pre-sold with the option
she wants. A deposit is in order to reserve a car, but I told her not
to place the deposit down until she completes the negotiation. So the
only place we can save money is in the financing package. Now, we have
to move fast and approach the negotiation in a knowledge matter.
Here's where I need help.

I would like to create an Excel spreadsheet with various loan
calculators. Web based loan calculator do not allow me to bring my
laptop into the showroom and reconfigure the numbers as the salesman
brings new deals to the table. The challenge become creates formulas
for the following scenarios.

The Salesmen goes to the Sales Manager and return with the following
offer.

Part I
$535 per month
60 month loan term
5.95% Interest

How much interest are you paying and what is the total price of the
car? You can not figure out the total cost of the car without knowing
the interest you paid. With the interest, you can subtract this amount
from the total cost and arrive at the dealer's true offer (price of
the car). I want to show the salesman what the total cost equates. So
he proceeds cautiously with the next offer.

Part II
You have good credit and your interest lowers to 4.95%.
How much do you save in interest expense? Total outlay? Car's price?

Part III
How much does your monthly payment decrease for every $1000 you put
down?

I have already figured out the monthly payment part, which is easy.
Plus, have reviewed the following formulas; PMT, PV, RATE, and NPER.
These salesmen are trained to confuse you, by changing elements of the
deal; adding fees; dealer fees; miscalculating the tax (caught them on
my last car with the tactic). Excel could help me create various
worksheets to anticipate these scenarios. Let me know if you have any
suggestions and examples.