University of Michigan (U-M) researchers claim "significantly flawed" analysis led the United States Postal Service (USPS) to downplay the environmental benefits of electric mail trucks.

The Postal Service has used its analysis to justify not making its entire fleet of next-generation mail trucks electric, which has drawn criticism from the White House, Congress, and environmental groups. U-M claims its researchers conducted a more rigorous study that still showed a much larger emissions reduction than the original analysis.

"U-M researchers conducted a cradle-to-grave greenhouse-gas emissions assessment—known as a life-cycle assessment, or LCA—of the two scenarios and reached some vastly different conclusions than the Postal Service did," the university said in a press release. The LCA has a broader scope than the original USPS study, which only considered emissions from actual use of the vehicles.

USPS Next Generation Delivery Vehicle - Oshkosh Defense

USPS Next Generation Delivery Vehicle - Oshkosh Defense

The debate over electrifying the USPS mail truck fleet started more than 18 months ago, with the surprise announcement that only 10% of the USPS next-generation delivery trucks would be electric. That led environmental groups and a coalition of states to sue the USPS.

The USPS gave into pressure this summer, and now plans for 50% of its initial procurement of the next-generation vehicles to be electric, and when combined with other types of vehicles in the fleet, 40% will be electric.

U-M researchers looked at the original plan of 10% EVs, comparing it to an all-electric fleet. They found that greenhouse gas emissions under the 10%-EV scenario would be 15% higher than estimated by the USPS, while emissions from an all-electric fleet would be 8% lower than the USPS estimate.

USPS Next Generation Delivery Vehicle - Oshkosh Defense

USPS Next Generation Delivery Vehicle - Oshkosh Defense

The U-M study also factored in estimated reductions in electricity grid emissions over the targeted 20-year lifespan of the new mail trucks. The USPS study appeared to assume the grid won't get any cleaner than the present—but of course it almost certainly will.

That makes a big difference. With grid decarbonization estimates factored in, U-M researchers predict that an all-electric fleet would result in up to 63% lower greenhouse gas emissions than the agency estimated, over the lifetime of the fleet.

These findings suggest the USPS should be electrifying at a rate much higher than even the raised 40% threshold, Greg Keoleian, senior author of the study, said in the release. The Inflation Reduction Act, which results in an extensive revamp of the EV tax credit and, for a time, a limited number of eligible EVs, included another $3 billion toward USPS electric vehicles—so the moment for a greater commitment is now.