I think he meant the Bolt EV was the fifth plug in from GM. That would be the the Volt, the ELR, the Spark, the CT6 hybrid, and now the Bolt EV. I guess six if you include the EV1. Just his response to the idea that GM was the company which killed the electric car. (He owns an ELR BTW).
And how could you forget GM Marketing. It's the group that gave us what might be the worst tagline in history for the Volt. How can you forget "More Car Than Electric"? LOL