Excel simulator

Hey Guys,

I'm looking for an excel sheet with following description:

This Excel sheet should describes a simulator for a car rental business.

The Goal is to determine automatically and based on "Available cash" when in the year the next cars can be bought to increase business' incomes.

Requirements:
1. One or more cars can be bought at once according to cash availability.
2. We also need an overview of current cars in the park.
3. Also note that a car lifetime is 30 months.
4. The simulator lifespan will be extended automatically based on last added car expiration date after 30 months from buying date
5. The line "Expenses" describes different expenses, which following are paid every 12 months for:
- Car insurance
- Bank interest
and "Initial capital investment" is paid once after 36 months
6. We need to see a line with cumulated incomes over time
7. We need to see at the current number of cars within each a period

Following variables muss be configurable:
A. # Financed cars
B. Car buying cost
C. Expected monthly incomes per car
D. Car insurance
E. Car lifetime
F. Initial capital investment: which is number of "Financed cars" * "Car buying cost" and is paid back once after 36 months
G. Bank interest which is a percentage of "Initial capitial Investment" and is paid annually

Please find attached something I've started working on.
Cheers,
joelka