Gas Price Spike Act of 2012 - Amends the Internal Revenue Code to: (1) impose an excise tax on the windfall profit from the sale of any crude oil, natural gas, or fuel which is the product of crude oil or natural gas; and (2) allow a tax credit for the purchase of certain fuel-efficient automobiles assembled in the United States by individuals employed under a collective bargaining agreement. Defines "windfall profit" as so much of the profit from sales of oil and natural gas as exceeds a reasonable profit. Establishes a Reasonable Profits Board to make reasonable profit determinations for purposes of applying the windfall profit tax.
Authorizes the Secretary of Transportation to make grants to mass transit systems, including bus and commuter rail systems, for reducing passenger fares.