The equivalent of $3+ a gallon? There are plans (Bechtel/Texaco/Sasol) to make diesel fuel from coal that would be close to the current DF price.
Come to think of it, is ethanol 2-3X more expensive?
I think ethanol is the equivalent of $1.30 - $1.50 gasoline. Ethanol is a good short term substitute, because many cars made in the last couple of years can use E85, (85% ethanol/ 15% gasoline) as well as gasoline, with no modification.
We can increase our use of ethanol, but it can't replace gasoline entirely, because we can't grow enough to make ethanol. Methanol can be made from natural gas, and is also competitive with gasoline. We can make M85 cars too.
While we're talking about nuclear reactors and other long term things, don't forget about simple things like bicycles, and walking.