In practical terms, while ebikes may have a slow top speed, they move through congested areas much more quickly, so for trip-substitution purposes, the efficiency is apples-to-apples. More direct routes at steady speeds is a real benefit to ebikes.

Much of the efficiency benefit is from the lower drag due to lower speeds, but if the purposed served is comparable, then it's valid. Just depends on what you're looking at.

FWIW, even at 30mph, ebikes are over an order of magnitude more efficient than a Model 3 at 70mph (<28 vs. 280 WH/mile). Zero (electric motorcycle) states 180 WH/mile at 70mph.

Agreed. That fits with my info. Pack a Model 3 with 5 people and go 30mph, and the efficiency per person is about the same as an ebike.

If you go steady speed the lower Cd and higher efficiency of the drivetrain might actually make it more efficient than the bike.

I think in this case it's small vehicles (low mass, low aerodynamic cross section) that are more efficient. Electric cars would only be marginally more efficient (~50% better) at low speeds due to rolling resistance (whose coefficient is basically constant with respect to speed) and parasitic loss from the computer, infotainment, climate control, etc.

Per seat, electric cars are generally much better than electric motorcycles and about half as good as much slower e-bikes (although if ridden at the same speed, almost as good).

Two things I can think of is gasoline powered motorcycles aren't that much more efficient than a Prius. And a Prius seats four. I suspect the same applies when you switch to electric[1].

The other one is the injuries per mile are much higher for motorcycles. One aught to account for that as well.

Side issue: Motorcycles are terrible from an emissions standpoint. Though of course an e-motorcycle would be better.

[1] Scaling factor vs size is highly positive.

It takes less energy to accelerate less mass. So the lighter your vehicle the more fuel efficient it is for the same speed/acceleration.

Going a lower speed is also more fuel efficient (depending on the engine, but it takes less energy) as you have a lower air/road resistance.