It says 0.1% efficiency, and uses 40MW. Does that mean it actually eats 50GW of fuel? If so... that makes it a bit useless. It also doesn't use diesel fuel, which means... I'd have to put rocket fuel in it? Well, nuclear fuel, probably. 40GW of that is like, 33 nuclear fuel per second, haha. Not exactly viable.
On the other hand, that's acceleration... so once it hits max speed it stops using so much fuel? Some power is still needed while traveling due to drag, but... oh, the train parts weigh 10 each. So drag is very low. It probably doesn't use much fuel after all.

Sounds like it'd just be easier to bounce into editor mode, plop down such a train, and just observe what it does.

()Just looking at one, it says: fuel consumption 40MW, and acceleration power 40kW so that's probably the 0.1% efficiency right there.)

Oh you're right, I misread the acceleration power. So it does use 40MW. Pretty reasonable fuel consumption overall, and it turns out it doesn't use solid fuel, it uses reactor fuel cells, which means you don't have to worry about oil consumption.
Vanilla trains use "burnable fuel", which is solid fuel including rocket fuel, nuclear rocket fuel, and the uncharged crystals in 248k. Diesel trains use "diesel fuel" which is only the three types in 248k(I'm not sure why the advanced forms have acceleration penalties...). And the maglev trains use "fuel" which restricts it to reactor fuel.