Focus on seven key things: the cash price of the car, the final selling price you'll pay, the down payment, the number and value of installments, all fees and insurance, early repayment terms, and what happens in case of late payment or car damage.
Key points
After considering these figures, inquire about the contract history: who bought the car first and when it was transferred to you.
A proper comparison between two offers should be based on your total payment and the terms of exiting the financing, not just the monthly payment.
The figures, fees and limits in this answer vary by bank and change over time — confirm them with your bank or the official source before acting.