ferries jordan/sudan?
 

are ther any? costs for a car?

No ferries from Jordan to Sudan. There is a ferry from Aqaba to Numeiba, Egypt; cost reasonable. But you can drive down to Jeddah (get Saudi visa) and take the ferry to Port Sudan. Don't do this when the hadj is on; all booked up.

I was under the impression that the Jeddah Suakin ferry actually continues up to Aquba - ie Aquba - Jeddah - Suakin - Jeddah - Aquba. Because it calls at Jeddah this means you still need a transit visa for Saudi so it doesn't avoid that problem. Given that, it might be easier to drive down the excellent roads through Saudi to Jeddah. Not certain thought, just what I heard.