Wal-Mart Stores (NYSE: WMT) has been advertising its "green" environmental initiatives for quite a while now. Light bulbs, organic foods and potting soils, electronics packaging materials and recycled products are all available at Wal-Mart these days, and although I believe it could do more to promote its green stance, the retailer's effort so far is admirable.

Wal-Mart will soon be taking the green approach to its transport fleet by using more natural gas-powered vehicles. The Peterbuilt 386 hybrid truck reclaims wasted energy from the engine and uses it for power later on. Just as in hybrid passenger cars, the truck's "regenerative braking" reclaims lost power for battery charging in the vehicle's electrical system.

Even an efficiency gain of a few percentage points is enormous considering the number of Wal-Mart trucks all over the landscape daily. Gains of five to seven percent can be made in efficiency with these new Peterbuilt transport vehicles, which is sizable all things considered. The system, not expected to be in full use until 2010, is a great move by a big retailer. What it needs to do is market this to its customers, even though it is not directly product related. Will it do this? It's not clear. But some marketing along these lines might be a good break from "everyday low prices."