Know one else has one as it needs a script to do it and the only one that works is "locked" and is payware. A loco can run for longer than the driver can drive.
Not true There are actually two payware creators (to my knowledge) that have locos with startup and shut down scripts, with fuel consumption. These are PhilC and Eldavo (UK locos).
There is, however, another (freeware) script going around that consumes fuel (no startup or shut down). I have used this on my VR and V/Line T class locos. Although not US locos, they are available, and do make use of this script
MPG= really depends on what its hauling and what kind of grade it's going up/down.
Check this link out http://pages.prodigy.net/rpearson/_wsn/page4.html It may be what you are looking for. The Loco consumes fuel but there is no startup sequence. I use it on some of my locos, but like what was said before, a loco can run longer than a driver can drive. It does take quite a while to consume a whole tank, but you can turn up the comsumption rate so you would have to fill up more often.