"Sen. Menendez has long been a proponent of the increased deployment of natural gas vehicles because they would reduce air pollution, increase energy security, and lower transportation costs," said the spokeswoman, Patricia Enright. "The senator's staff first began working on this issue in early 2009 and introduced the bipartisan NAT GAS Act later that year."She said it was unclear whether the senator will continue to support the bill he had sponsored. Melgen's attorney, Ogrosky, told the AP in a statement that "Dr. Melgen has never discussed his involvement with Gaseous Fuel Systems Corp. with either Sen. Menendez or his staff." An SEC document filed last week by GFS showed that Melgen remains on the company's board of directors. An earlier document filed by the firm in May 2011 was the first to show Melgen as a director. That SEC record showed a $6 million investment in the firm from two unnamed individuals. The company's top executive, Ken Green, said Melgen is a key investor but has had no influence on the company's decision-making and has not attended any director's meetings since he joined the firm. "Dr. Melgen hasn't ever been to our offices, not once," Green told the AP. "He's a passive investor." Green said the Senate bill that Menendez supported would provide only limited help to his company because most of its provisions are aimed at heavy on-road vehicles like truck rigs and bus fleets. GFS has pioneered an engine conversion system that can be installed on diesel-fueled vehicles, but Green said it is marketed exclusively for off-road equipment, such as massive mining trucks. The tax credits proposed by the bill would do little to offset the cost to buyers of the off-road trucks, which can cost as much as $8 million, Green said. "This bill won't do much of anything for us," he said.