Flying "cars" are far from real, The Martin Jetpack which the author has mentioned is noisy, expensive and only has 30 minutes (31.5 miles max) operating time. However, there's much room to improve current transportation system, new technology and government regulations are constantly pushing fuel efficiency. Mass production air-based vehicles aren't viable unless energy production becomes cheap enough.

The next viable transportation system may be vacuum maglev train. The world already have Superconducting and normal conducting Maglev technology (JRC and Transrapid respectively) and mankind have built countless tunnels and bridges and concrete structures.