The most efficient is the Hyundai Ioniq 6 Long Range RWD, followed by Lucid Air Pure AWD or Touring AWD, according to https://www.cnet.com/roadshow/news/most-efficient-electric-c.... Tesla lies about EPA range, so I wouldn't trust the Model 3 or Y at #3 and #4.
> a 48 kWh battery providing 420 km CLTC range
The Tesla Model 3 is currently the most efficient EV, and does ~4.5m/kWh, which is ~7.2km/kWh (ballpark; precise figures vary by source).
48kWh x 7.2km/kWh would give 346km range, or ~82% of 420km.