Xpeng Heitech, a flying car start-up backed by electric vehicle maker Xpeng Inc, says it will deliver flying cars to customers in 2024. The start-up, founded in 2013 and funded by Xpeng and Xpeng's chief executive He Xiaopeng, employs 400 people and will expand its workforce to have 700 people by the end of this year, company founder Zhao Deli told World New Energy Vehicle Congress. Xpeng Heitech's model will also be able to drive on the road, Zhao said. The electric flying car will be able to drive more than 600km on the road with a single charge but…