For the most part, electric vehicle discussions center around passenger vehicles, but companies like Tesla, Daimler and Cummins are working to electrify larger trucks, like big rigs. One of the pressing questions is how those companies will handle charging. Some have speculated that Tesla's first fleet will rely on customers like Pepsi and UPS to build on-site chargers. Networks of high-speed charging stations, like Penske's, could help speed up the adoption of electric semis.