With each carrier having tens of thousands of vehicles in its global fleet, an order from a package delivery giant can launch a startup on the road to manufacturing scale and profitability and serve as a marketing tool to win orders from other big customers.

"Everyone is looking for their golden ticket," said Steven Merkt, president of transportation solutions at sensor, connector and electronic component maker TE Connectivity Ltd, which works with all the startups and provides technical feedback on designs. "If you don't have scale, you're going to get squeezed out pretty quick."

Hunting for the 'next Tesla', investors have poured billions of dollars into electric vehicle startups, with mixed results. Unlike Tesla, which enjoyed a headstart of years over traditional carmakers, commercial electric vehicle startups are racing against time as major manufacturers such as Ford start to bring competing products to market and others...