My guess right now is for a hyperloop concept is a magnetically accelerated vehicle that has ground effects and inductive energy transfer for onboard fan motors that operates within a deep trench.
Ground effect vehicle - Wikipedia, the free encyclopedia
Basically a big bobsled with wings. Instead of requiring enough thrust on board to accelerate, the departure from the station is like being shot from a railgun. Kind of like the Ferrari Rossa roller coaster:
Formula Rossa | World's Fastest roller coaster| Ferrari World Abu Dhabi
That way the vehicle doesn't have to carry big enough engines to bring the vehicle to speed. Then, it has enclosed fan thrusters that are electric and it uses inductive transfer to zap charge some ultra capacitors. This helps maintain the ground effect "flight" as the vehicle decelerates from the initial boost. The wings change shape, changing from a little bit of downforce to increasing lift as the vehicle slows. The trench is deep and broad enough so that the vehicle is extremely unlikely to come out of it, like a bobsled. The final configuration of the track may even look like an infinity symbol (hence loop). Since the vehicle "flies" the track doesn't have to be extremely expensive unlike a monorail or a maglev. It doesn't even need to be reinforced concrete, it could be more like salt flats. If it had to, it could actually fly the length of the loop using just the fan motors, but it would be much slower and not nearly as fun.
All of the energy consumed is electric and therefore it can be powered by photovoltaic panels and recycled Tesla car battery packs.
Some reasons I get to this conclusion:
To hit speeds over 300mph with reasonable cost and efficiency, ideally the bulk of the energy to get to speed is not on board. Therefore railgun acceleration.
To hit speeds over 300mph without building ultra expensive track, it is better to be in a roughly prepared trench that is big, deep, and wide enough (think bobsled roller coasters). Ground effect is terrific for increasing efficiency and the fact that you are riding on air is going to be far more efficient that dealing with the friction of wheels at that speed. Maglev would be even better, but the cost of laying down that much maglev track would be cost prohibitive (think of just the metal costs). Zapping in electricity through inductive charging to ultra capacitors means that the vehicle weight can be kept down - it doesn't have to carry as much energy.
