One is H.R. 1380, known as the “New Alternative Transportation to Give Americans Solutions Act,” or “NAT GAS Act” for short.
The other is H.R. 1687, the Open Fuel Standards Act.
The approaches adopted in these two pieces of legislation are very different and Dr. Zubrin does a good job of highlighting their points:
"The NAT GAS Act, which is strongly supported by oil and gas tycoon T. Boone Pickens, would provide a $7,500 tax-credit subsidy for the purchase of natural-gas cars, as well as a further subsidy to their manufacturers of $4,000 each, for a total of $11,500 per car."Check out the full review HERE.
"...the Open Fuel Standard bill does not choose a single winner, and would not cost the treasury anything. Instead, it stipulates that within several years the majority of new cars sold in the U.S. must give the consumer fuel choice by being any one of the following: full flex fuel (i.e., capable of using methanol, ethanol, and gasoline), natural gas, plug-in hybrid, or biodiesel compatible"
Source: National Review Online