A few thoughts not in any order. First part of the savings from dropping an engine is the fuel used. Now with your first idea, no extra fuel would be used. But if another option were choosen, that might not be true. Plus now there is the cost of batteries and maintaining them and you've got to find space to put those batteries into the cars. That could mean the loss of revenue space. I'm not positive, but for some reason I believe that the refer cars actually have a motor and therefore a small fuel tank. So if that is true, then your fuel savings wouldn't be as substantial.That being said, thank you for bringing me up to speed. Those ATSF Hi-Levels are what I rode on that first Amtrak trip and they will forever be my favorite cars. I didn't know that self-powered cars had been tried before but don't you think that with today's technology something better could be developed? Refer cars run all over the country- sure they fail from time to time but most of our produce gets through. I guess what I was aiming at was saving HP on the head end. I may be wrong but I thought that running the HEP draws off of the Locomotive's ability to pull. The P42DC is an astonishingly powerful unit yet most LD trains use two of them. The SWC uses three, (the same number of SDPs it used in the 70s and F40s in the 80s), most of the time. Is this for reliablility reasons? I read somewhere that Amtrak saves 1 million dollars a year by chopping one unit off of the Texas Eagle. If that's true, (and I don't know if it still only uses one but it was last year when I rode it to St Louis), then a hard look needs to be taken at the other routes.
Next, Amtrak often doesn't always analyze things properly. They may notice the fuel savings by dropping one engine, but not stop to notice that fuel consumption went up on the remaining units. Yes, they did save on wear and tear on that dropped unit, but it could also cost them in times of failure by not having that extra unit around. I'm not sure about the $1 M, but it certainly could be possible.
Next, one reason for more engines, isn't just the extra pulling power it's for tractive effort. If you have more wheels on the ground actually helping to pull the train along, you can climb steeper hills and do it more swiftly. Then there is the general idea of accelerating back up to track speed after a stop. Takes longer to do that with one engine vs two. That could mean slightly longer schedules.
Next, in the case of the P42, yes HEP does take away power from the prime mover (the main engine). In the case of the F59PHI locomotives, there is a seperate smaller diesel engine that provides HEP, therefore there is no drain off of the prime mover. And an extra niceity is that if the main engine fails, you can still provide HEP while waiting for rescue.
Finally, because of Amtrak's recent record of engine failures due to some maintenance cuts (not safety issues), CSX and I believe BNSF have demanded that Amtrak run with two or three engines depending on the route.