In reply to STM317 :
I don't disagree with you statement in general that EVs are better overall. But the issues I tried to convey in the section you quoted was that the USPS is not being given the funding it needs to do an EV fleet properly. Secondly, based on my own agencies analysis of going EV.
Pause, I support the idea of maximizing the EV fleet as it at least gets us headed towards a better energy infrastructure. So I am not anti EV. I just see everyone missing the point that the USPS is not getting funded to be cool like that. Heck I think the leadership in my agency have a hard time with the cost estimates.
Resume. Within my agency we have many uses that just can't go EV because a lot of our particular fleet must be able to tow equipment. We just haven't seen an EV truck/van that is capable of doing the distance with our loads without multiple hour stops along the way. At the facility closest to me they have 3 dually diesels, and maybe 15 heavy duty trucks all being fully used to haul equipment or good sized boats regularly, as in some groups have to delay work because we need more trucks. So we have maybe 40-50% of our fleet already excluded from EV transition, FOR NOW. So for the other half of the fleet, the internal real property investment to switch to an EV fleet has been repeatedly evaluated at my own agency. My agency has presented those costs to our Department and so far there isn't support in Congress and I suspect the public for that type of price tag, we will see with this administration. We assessed several scenarios including maximum offsite recharging, Public Private partnerships to have the local electrical utility build and manage it on our property, and maximum onsite recharging. They each have large costs and public domain/environmental/social challenges. For my agency the need for a government employee to go investigate an earthquake/flood/forest fire where there is no longer power is a real need so unlike the public that can just not go there as they know they can't charge their car some people in my agency have the specific job to go there and take fuel with them or are linked up with DOD assets to ensure they can refuel. We would need to replicate that continuation of government built upon petroleum access so that may mean rather awesome sized solar charged battery backup systems, wind power, or Diesel generators sized to not just sustain a building but charge all the cars. I don't think my local post office has enough real property to just cover it with solar panels and being in the city we won't be likely to just stand up a wind turbine. So the only choice is working with the utility to increase our power and that would only happen with paying the costs to ensure that all of the surrounding public don't see significant increases in their electrical bill because USPS demand is so high from 5pm until 9am. That is even if the local utility can even handle the variance.
So from an environmental standpoint we felt, back in 2014 for sure when I was involved, that going out to cover federal lands with emergency power generation systems would not just sail through NEPA review. The costs would be highly variable, it was not a nice clear cut number as your graphic shows at $40,000 per vehicle but some greater number than that.
I have a feeling that if, lets say, the Niagara power generation grid blacked out again as it did in 2003, not everyone would be just fine with not getting any mail for the duration of the blackout because the post office can't charge any of their vehicles. But maybe we will have mini fission reactors for each USPS building by then. 
Finally I wish the head of the USPS would just have a press conference and say. We at the USPS want to maximize our electric vehicle fleet which we project would be between $700,000,000 and $800,000,000 over 8 years. Lets go! Then in the magical dream world the public outcry would spur a special vote to give the USPS a solid $10,000,000,000 to lead the Federal government into an electric power based infrastructure. Then nobody would care about the NGDV anymore.
