Most Tesla owners charge the car only to 80%. The UI in the car for setting the limit encourages this by marking the zone from 60-80% as "Daily Usage" and the 80%-100% zone as "Trip".
When you purchase the car the default is also set to 80% and the delivery person tells you that you should usually have it set to 80% unless you are going to go on a long trip.
It's hard on lithium batteries to charge them up all the way and so Tesla and maybe some of the other car companies spreads the charge over more batteries to make their lives longer.
