Kirst
No personal experience of this. However, having read the above post in conjunction with your other under the Welcome thread, I come to this conclusion.
The Fiat dealer acts as a credit broker who can offer a few options. The first option has been declined due to the credit check caused by the Welcome issues. The dealer then may have a few other options but these may be with 'sub prime' type lenders at a higher apr%.
I think if you went with the other options at this stage, you may experience similar issues to those with Welcome. The way these companies operate is to offer a high interest but affordable loan rate and then to massively increase the rate, if you were ever late with a payment. Personally I would never trust these companies.
Huckster