Volt's engineering is fine. That the auto industry was and is still trying to figure out how to market these, is not news. Honda is not exempt ... the first attempt at the Accord hybrid was a dud, the first Insight was a dud, and some of their current hybrid models are stupid expensive. And, Honda still needs to recover from their earlier hybrid models having well-documented high failure rates of the battery system ... something which the Volt has NOT had.
No argument that Tesla has gotten a lot of things right, including how to market them - fast-charging availability had to go hand in hand with the vehicles themselves. Rushing products to market and paying the price later, has not been one of them. Inability to support their customers in the field (with prompt availability of replacement parts) has been another issue.
Let's see what happens to Tesla when the mainstream manufacturers come up with competitive products. They're coming ...
https://www.topgear.com/car-reviews/jaguar/i-pace
https://www.topgear.com/car-reviews/audi/e-tron