Route Not Optimal

🚧 THIS IS A TICKET MIGRATED FROM UPVOTY. The original ticket and comments will be available for a limited time over at:
https://abrp.upvoty.com/b/report-a-bug/route-not-optimal/
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With my 2021 Standard Range LFP Tesla Model 3 linked, ABRP chooses a complex mainly inland route from Perth to Kalbarri and specifies a slow speed along a lot of it. (See screenshots). I’ve tried forcing the car to go to the coastal chargers, but it then heads back inland!
If a generic Standard Range Model 3 with LFP and heat pump is used, ABRP picks the optimal coastal route which does not require any speed reductions.
What is forcing ABRP to take the longer and less optimal inland route?
I’ve had a number of people to look into this and none of us can work out what is going on.