The Bush administration had blocked California, as well as Maryland and a dozen other states that chose to follow California's lead with a "Clean Cars Program," in imposing stricter emissions standards than what federal law requires. Obama will reverse the policy, the New York Times reported last night.

WASHINGTON — President Obama on Monday will direct federal regulators to move swiftly to grant California and 13 other states the right to set strict automobile emissions and fuel efficiency standards, two administration officials said Sunday evening.

The directive makes good on an Obama campaign pledge and marks a sharp reversal from Bush administration policy. Granting California and the other states the right to regulate tailpipe emissions is one of the most dramatic actions Mr. Obama can take to quickly put his stamp on environmental policy.

The presidential orders will require automobile manufacturers to begin producing and selling cars and trucks that get higher mileage than the national standard, and on a faster phase-in schedule. The auto companies had lobbied hard against the regulations and challenged them in court.

From the Maryland Department of Environment's Clean Cars Program site:

Maryland Clean Cars Program

In early 2007, a bill was introduced in the Maryland General Assembly to reduce emissions from motor vehicles. The legislation passed both houses and Governor Martin O’Malley signed the Maryland Clean Cars Act into law on April 24, 2007. On November 19, 2007, the Clean Cars Act was adopted into Maryland regulations.

The Maryland Clean Cars Program adopts California’s stricter vehicle emission standards. These standards will become effective in Maryland for model year 2011 vehicles, significantly reducing a number of emissions including volatile organic compounds (VOCs) and nitrogen oxides (NOx). The VOC reduction is expected to be 3.4 tons/days greater than the Federal standards and the NOx reduction is expected to be 2.9 tons/day greater than the Federal Tier 2 standards. VOCs and NOx emissions cause Maryland’s ozone problems.

Currently, the Clean Cars Program represents the only program that directly regulates carbon dioxide (CO2) emissions. Transportation is the fastest-growing source of CO2 in the U.S. and CO2 is the most prevalent GHG. In Maryland, approximately one third of CO2 emissions are emitted from cars.