How long will electric car batteries last?
Because they are such a  large investment, electric car batteries, the ones used for traction, are typically managed so they target an 8 year life. 

This is done by providing more nominal Ah of storage than would be needed to achieve the Ah specification in 'normal' consumer use (laptop, phone, drone). In the early years, the battery pack is operated avoiding full charge and full discharge, which prolongs its life substantially. Later on, as the battery degrades, the charge management system allows a larger state of charge swing, to deliver the same specified Ah, until at end of life it's using the full voltage swing allowed.