If you believe the headlines, traditional automobiles are speeding toward a dead end. All those V8s, V6s and turbocharged vehicles we've grown to love will soon be replaced by squadrons of clean, whisper-quiet, all-electric vehicles. And if you believe the headlines, the environment will be much better off.

Policymakers at every level have done their part to push electric vehicles by creating a tankful of subsidies. Thanks to laws signed by both George W. Bush and Barack Obama, electric-vehicle buyers can feast on federal tax credits of up to $7,500 that reduce the initial purchase cost of their vehicles. Not to be outdone, many states also dangle their own mix of goodies for electric vehicle buyers, including purchase rebates as large as $5,000, additional rebates for vehicle chargers, and free use of public charging stations--which, of course, are only "free" because they're subsidized by ratepayers and taxpayers. Some states even give electric vehicles preferential access to carpool lanes.

Then there are the electric vehicle mandates. In January, California Gov. Jerry Brown decreed that 5 million electric vehicles must be on his state's roads by 2025, along with 250,000 charging stations. Eight other states are following California's lead. One California lawmaker has even introduced legislation to ban all internal combustion vehicles by 2040.

All of this might make sense if electric vehicles, as their supporters claim, were truly likely to reduce air pollution and tackle climate change. But are they?