A personal loan from a bank or other lender.
This method can work out substantially cheaper than taking the dealership finance.
Example
Here's an example of a loan agreement on a £10,000 loan over 5 years at 5.5% APR:
You would make 60 payments at £190.39 per month. The total amount repayable would be £11,423.40, including interest and fees of £1,423.40.
Pros
Cons