Yeah, according to the EIA (note: different than the IEA), "the US would change from the world's leading importer of oil to a net exporter over the next five years."
http://www.bbc.co.uk/news/business-22850607
Still, I find it easy to believe that fracking and shale and tar extraction technologies and equipment and expertise would be lost during the apocalypse (whatever it's exact nature may be). Especially if you cut off access to foreign suppliers, and there are food riots where the refineries are, I can believe that the remaining oil in north america would get pretty stinking expensive until the recovery catches up enough. It's plausible to me that a coal mine would be easier to keep operating, and therefore electricity would be a better deal.
Bottom line, I think the fundamental "gas is really expensive" effect could be maintained with a small change of the flavor of stuff that justifies it.
But it also wouldn't be bad to model electric engines as more powerful but with more limited range (e.g. batteries having higher space/weight per mile of range provided than gasoline). Especially if fewer people are traveling long distances due to intervening wastelands, and if the few stable interstates have regular fortified truck stops for recharging, I can believe that electric cars would be attractive even if the gas shortage isn't as acute.