GoodCleanTech, June 4, 2010 — Verizon has purchased 576 Chevrolet Silverado Two-Mode Hybrid full-size pickups in an effort to further green its truck fleet. The two-mode Silverados, equipped with Vortec 6.0-liter V-8 engines, achieve an EPA estimated 21 MPG city and 22 MPG highway, which represents about a 40 percent reduction in fuel use compared…