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).