Overall use of clean fuels and advanced vehicle technologies is rapidly progressing, according to a recent survey of 250 public, private and municipal fleets. But industry experts added that many thorny issues remain.

Gladstein, Neandross & Associates made the assessment in its third State of Sustainable Fleets Market Brief.

Fleets cited their move toward environmental sustainability and carbon reduction, and the need to find more cost-effective transportation options given today’s record-breaking gasoline and diesel fuel prices…

The report also pointed to the accelerating effect of record-setting government funding and legislative support at the state and federal levels. Oregon, Washington, New Jersey, New York and Massachusetts have adopted rules based on California’s that require truck makers to sell increasing numbers of zero-emission trucks.