In FY2022, fuel consumption was 221 million gallons of gasoline equivalent, with gasoline or diesel making up 99%. USPS fleet greenhouse gas emissions (GHGs) made up 70% of overall GHGs for federal fleet vehicles in FY2022.

50-60% of all mail is marketing slop

Mail delivery vehicles have to travel roughly the same paths as long as there is most anything to deliver.

That's what makes it a public service.

Junk mail just makes stamps cheaper. That route had to be driven anyway. You have generally what amounts to a right to put a stamped letter in your box at the end of the driveway, put up the flag, and get serviced. The route has to be driven regardless.

We could eliminate all marketing mail, make a large push to make all billing digital, and USPS would still have to drive most routes most days.

A fix would have to reduce service significantly, or introduce a new "Register for pickup" process to signal your need of service.

We could have also made those brand new mail vehicles hybrid or something.

Honestly I'd be surprised if it's that low. My guess is by weight its closer to 85%-95%.

Your numbers show exactly what I was guessing to be true though. Incredible this has never been enforced.