US ride-hailing company Uber Technologies Inc and South Korean automaker Hyundai Motor Company have teamed up to develop electric air taxis, joining the global race to make small self-flying cars to ease urban congestion.

Global players such as Germany's Daimler, China's Geely Automobile and Japan's Toyota have all unveiled investments in start-ups that aim to deploy electric flying cars capable of vertical take-off and landing (VTOL). But there are big technological and regulatory hurdles to the plans.

Uber and Hyundai, for instance, gave different timelines for commercialisation, underlining these challenges.

“We've been making steady progress towards a goal of launching Uber Air by 2023,” Eric Allison, head of Uber Elevate, said at this week's Consumer Electronics Show (CES) in Las Vegas.

Euisun Chung, executive vice-chairperson of Hyundai, expects commercialisation of urban air mobility service in 2028, saying it takes time for laws and systems to be put in place.

Hyundai is the first carmaker to join Uber's air taxi project, which also counts Boeing subsidiary Aurora Flight Sciences among its partner firms.

Hyundai will produce and deploy the vehicles, while Uber will provide aerial ride-share services. Though the air taxi would have a pilot initially, it would ultimately be fully autonomous.

Uber, which has partnered with eight companies on its air taxi project, however, acknowledged it would be “unrealistic” to expect all its partners to go to market at the same time.

“Our plans for our limited commercial operations in 2023 will likely involve other partners,” Sarah Abboud, communications manager at Uber, said.

Hyundai unveiled a concept electric aircraft developed with Uber at CES, with the self-flying electric car, named S-A1, designed to carry up to four passengers, with a pilot, and fly on trips of up to 100km.

“The overall cost to produce and operate UAM (urban air mobility) vehicles should be really low enough for everyone to enjoy the freedom to fly,” Shin Jai-won, head of the Urban Air Mobility Division at Hyundai Motor Company, said.

Air taxis come in several shapes and sizes — electric motors replace jet engines, and aircraft have rotating wings and, in some cases, rotors in place of propellers.

The urban flight market will exceed the current number of commercial aeroplanes flying around the world — about 25,000, Hyundai's Shin, a former Nasa engineer hired by the automaker last year, estimated, without giving any time frame.

Last year, Hyundai pledged to invest 1.8 trillion won (about R21.3bn) in what it called “urban air mobility” by 2025.

Uber Air's long-term goal is to be cheaper than the cost of driving. In the US, the current cost of running a car, excluding the purchase price, is 49c (R7) a mile (1.6km), including fuel, parking, insurance, repairs and so on

Using Uber Air will cost about R84 a mile when it launches, but its ultimate goal is to reduce it to R6.50 or less a mile, bringing it into the realm of affordable mass transport.

To handle its fleet of flying taxis, Uber Elevate aims to establish a network of Skyports that can eventually handle up to 1,000 landings an hour.

In Europe, flying taxis got a step closer to reality when a Volocopter VTOL prototype was demonstrated at Daimler’s headquarters in Stuttgart, Germany, in September.

The German start-up aims to have autonomous air taxis in the sky within a few years and is financially supported by Daimler and Geely.

Boeing is working with Volkswagen's sports car brand, Porsche, to develop a concept electric flying vehicle that can transport people in urban areas.