, a division of Celadon Group, says participation in its fuel rebate program grew from 180 member companies in April to 400 companies at the end of May.

Activated members now in the fuel program represent more than 24,000 tractors. The company also announced a third round of monthly fuel rebates., formerly, is a business-to-business membership program that provides discounted fuel, tires, equipment and other products through its Internet web site.