PETALUMA, United States — UPS is swapping some of its familiar big brown trucks for smaller, greener vehicles.

The Petaluma, Calif., UPS branch has leased 42 Xebra electric cars and trucks produced by Santa Rosa-based ZAP. The Xebras will be used to deliver small packages, mostly in congested areas where UPS trucks typically have problems navigating and parking.

The three-wheel, all-electric Xebras can zip along up to 40 mph and have a range of 25 miles per charge. UPS is setting up distribution points for vans to transfer packages to the Xebras

"Packages go from the airplanes, to the tractor trailers, to the delivery vans, then to the drop-off nodes. From there the ZAP trucks make the final delivery to the consumer in a zero-emission vehicle that costs less to operate," said ZAP CEO Steve Schneider. "It's a perfect example of how green technology can help corporate America's bottom line."

The ZAP vehicles are the latest green additions to UPS's vehicle fleet. Last year, UPS added 50 hybrid electric vehicles to its fleet, and uses more than 1,600 alternative fuel vehicles in its fleet of over 93,000.