I think the fact that hovercraft and the Concorde ate shit about the same time is directly related to the thunderous amounts of energy both consumed.

Humans can produce about 1/10th of a horsepower indefinitely. Nobody really thinks about this but the fact of the matter is, we're good for about 75 watts. You, normal human, lack the physical fitness to keep your Macbook Pro charged. In order to charge up your Chevy Volt to the point where it could go 100 miles, you would have to pedal a stationary bike for 42 hours (assuming that stationary bike was 98% efficient). On a non-stationary bike I could do 11mph all day long - If we both started pedalling I would be there for 33 hours before you turned the key.

Fast... costs. The SR-71, with two humans at cruise, consumed twice as much energy as the Queen Mary, a 12-deck, 2100 passenger 77,000 long ton transoceanic passenger liner. I've got the sales dept's advertising costs for the failed Boeing 2707 and they are staggering.

The MV Walla Walla requires 11,500 HP to transport 2000 passengers and 188 vehicles at 18 knots. The Victoria Clipper III requires 3200 HP to transport 250 passengers and zero cars at 25 knots. There are no car ferries between Seattle and Victoria anymore because they're too damn expensive.

The "Regent Seaglider" is a cartoon at this point. Kenmore Air flies deHavilland Beavers - they require 450HP to haul six people at 137 knots. You could halve that in ground effect, and probably halve it again because of modern design - you're at 20HP per person.

The big dumb car ferry has you beat by a factor of five before we consider the fact that it's also hauling your damn car.