Why does the manual say to start preconditioning 20 minutes before fast charging when the car automatically starts 45 minutes before arrival?

[codys21]

Basically title. The manual (and also the pop-up when manually clicking precondition) says to start preconditioning 20 minutes before fast charging but the car automatically starts 45 minutes before arrival when routing to a fast charger.

Why the difference and which is "right" or "better"?

 

[Buffalo Bob]

The car's navigation system does not adjust the 'automatic' preconditioning time to match the environmental conditions. My guess is that 45 minutes was viewed as enough time to prep for all but the very most extreme conditions, while 20 minutes is a 'good enough' prep time to take the edge off of most commonly encountered conditions. As examples, preconditioning is not even necessary on a comfortable SoCal day, while 45 minutes would probably be barely enough on a Fargo winter day or a Palm Desert summer day.

 

[borski]

20 is a minimum; 45 is ideal. But it depends on conditions, how long you’ve been driving, etc. I usually try to do 45 if the car doesn’t know about my charging station.