The only way I would do that is if the interest rate is almost zero. I honestly think you'd get a better deal by financing using a traditional auto loan because secured loans (auto, mortgage, etc.) have a lower rate than unsecured loans. If you put the same amount of money down and still financed for say 60 months. I think you would come out ahead. Especially with the final payoff number that includes all of your interest payments.
I am not knocking Discover at all. I have used them in the past to consolidate and pay off some higher interest debt in a very structured manner. I just do not think they are the way to go in this case.