For a 1-person flying vehicle,

                             Power/Mass
                              Watts/kg

Minimum for fixed-wing flight   100
Minimum for hovering flight     200
Minimum vehicle power/mass      300   Should be easily able to hover. Use 1.5 times the minimum                                                                                 power/mass to hover
Lithium-titanate battery       4000
Electric motor                 8000
Electric generator              100

Batteries easily have enough power/mass to fly, and electric generators don't.

The minimum power/mass required to fly scales as Mass^(1/6), and this sets the maximum mass of an aircraft. Because the scaling is so weak, heavy aircraft are possible. A 40-seat electric flying aircraft is possible.

The range will be poor. Maximum 100 km. You can't fly over the flyover states with an electric aircraft.

Electric flying cars are a great idea because batteries are more reliable than gasoline motors. Also, a battery can support many propellers, and the more propellers, the better. Increasing the number of propellers increases safety and also reduces the minimum power/mass to fly. The minimum power/mass to fly scales as N^{-1/6}, where N is the number of propellers.

jaymaron.com/flyingcar.html [jaymaron.com]

The Wright flight was made possible by advances in the power/mass of motors. The Wright aircraft motor has a power/mass of 116 Watts/kg, which is just barely enough to fly.
At the time, this was the motor with the best power/mass. A WW2 1940 Japanese Zero engine has a power/masss of 1400 Watts/kg, which was larger than for American engines. Today, a Ferrari gasoline motor can produce 8000 Watts/kg.

It has been true for 20 years that lithium-ion batteries have a power/mass large enough to fly, but the obstacle was price. Only recently have lithium-ion batteries become cheap enough for electric aircraft.

Humans have a power/mass of 15 Watts/kg, way not enough to fly.

The reason the unit of power is the "Watt" is because James Watt invented mighty engines.

Aircraft are loud, even electric aircraft.

For ground vehicles, gasoline vehicles are loud and electric vehicle are silent. This is the most important quality of electric vehicles.