From Guardian UK:  One-quarter of all the maize and other grain crops grown in the US now ends up as biofuel in cars rather than being used to feed people, according to new analysis which suggests that the biofuel revolution launched by former President George Bush in 2007 is impacting on world food supplies.

The 2009 figures from the US Department of Agriculture shows ethanol production rising to record levels driven by farm subsidies and laws which require vehicles to use increasing amounts of biofuels.
http://www.guardian.co.uk/environment/2010/jan/22/quarter-us-grain-biofuels-food