NASCAR is still determining how it would use hybrids. They may be better suited for shorter courses with more turns and braking, which would put the regenerative braking to use. The hybrid tech would likely be used in parallel with internal combustion engines to add power, rather than solely improve gas mileage. For instance, Probst says the hybrid tech might provide a kind of strategic supercharge that could be used to provide extra power to complete a pass.
NASCAR says it's taking things one step at a time. Its Next-Gen race car just completed its first on-track tests and is set to debut at the 2021 Daytona 500. It will release its Next-Gen race car guidelines in 2021. Then, we'll likely see some type of hybrid tech. NASCAR isn't alone in this push. IndyCar is planning to switch to 900-horsepower hybrids in 2022 as well.
Update 10/11/2019 2:10PM ET: NASCAR contacted us to let us know they were misquoted in TechCrunch's story. We've updated our story to reflect that the company never discussed fully electric racing.