A coalition of environmental groups and over a dozen states filed lawsuits Thursday against the United States Postal Service (USPS) over plans to replace mail trucks with a majority-gasoline fleet.

A new mail truck design from defense contractor Oshkosh was unveiled in February 2021, with plans to make just 10% of the fleet electric. That immediately drew criticism, as the outgoing Grumman "Long Life Vehicle" (LLV) trucks were widely expected to be replaced by fully electric trucks.

Now a lawsuit filed by Earthjustice, CleanAirNow KC, the Sierra Club, and the Center for Biological Diversity in the Northern District of California—joining that filed by 16 states—alleges that the USPS signed a contract with Oshkosh before a proper environmental analysis was conducted, or before accurate costs for electric vehicles were determined.

U.S. Postal Service Grumman

U.S. Postal Service Grumman

The analysis used to justify the plan for a mostly-gasoline fleet included unrealistically high battery-cost projections, with gas-price projections that were unrealistically low, the Sierra Club said in a press release.

The USPS used an estimate of $2.19 per gallon, projected to increase to $2.55 per gallon by 2040, according to the Sierra Club. The analysis also assumed suitable EVs would achieve no more than 70 miles of range, the organization said.

Gasoline versions of the new mail truck are expected to average 8.6 mpg with the air conditioning running, which is worse than the Grumman LLV trucks got when new, the Sierra Club noted. And because mail trucks travel an average of 20 miles per day and are parked in a centralized location at night, they're "especially prime for electrification," the group argues.

USPS Next Generation Delivery Vehicle  -  Oshkosh Defense

USPS Next Generation Delivery Vehicle - Oshkosh Defense

In addition to the lawsuit by the environmental groups, 16 states including California, Connecticut, Delaware, Illinois, Maine, Maryland, Michigan, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, and Washington filed their own lawsuits against the USPS Thursday, along with the District of Columbia, City of New York, and California's Bay Area Air Quality Management District.

The USPS initially pushed ahead with its plan despite requests from the White House, EPA, and members of Congress to reconsider its environmental analysis and add more electric vehicles to the order.

Recently the USPS upped its order of electric trucks amid controversy, but it's unclear whether that actually means more for the entire production, given that it doesn't rework the contract.