Battery state-of-health
The single biggest value driver. Gen 1 (2010-17) 24 / 30 kWh packs show measurable degradation by year 5-7; Gen 2 (2018+) 40 / 62 kWh packs hold up better. We read state-of-health, not just dashboard range. Bring a recent battery report (Leaf Spy or dealer printout) for the firmest offer.