APR is Annual Percentage Rate, which is the full annual cost of a loan, including all administrative and service charges & fees. When car manufacturers offer cheap APR financing, they are offering it to those with good or perfect credit, and typically for a 36 month term. Anything different and your rates climb. If you want your car payments stretched over 4 or 5 years, not only so you pay interest longer, but you will be charged a significantly higher interest rate.
Sometimes manufacturers offer you a choice of cheap loans or a discount or rebate on the price of the vehicle. Those with bad credit, who will not qualify anyway for the cheap loans, should probably take the discount or rebate. If you've pre-arranged bank financing, use this rebate to pay down your loan. If the bank won't let you do this, use it to pay more into your RSP to save on your income taxes!
The "Subject to Financing" clause appears on paperwork of all new car loans. It means the deal is not done, yet you think you are signing a contract. Then 2 weeks later the car dealer calls saying "your new car loan fell through" at the advertised APR rates and you need to re-qualify for a more expensive loan. If they tell you they found alternative financing with a lower monthly payment, check the paperwork that they just didn't stretch out the loan repayment period