Washington Post: PRESIDENT OBAMA has called for 1 million plug-in electric vehicles on U.S. roads by the year 2015. This sounds ambitious, until you consider that there are 241 million vehicles in operation, according to the R.L. Polk automotive information service. Yet even Mr. Obama’s modest goal — boosting plug-ins’ share from zero to less than half a percent of the huge U.S. auto fleet in five years — is looking increasingly impractical and, for taxpayers, expensive. At least that’s how we …