Freedom EV is a free/open software stack intended to replace the software in your electric vehicle, it's been tested on a Tesla Model X and should work on a Model S, if you can get root.
Electric vehicles are very exciting but the same informatics and versatility that make them exciting also invite manufacturers to add all kinds of antifeatures (like batteries with plenty of charge remaining that refuse to power a vehicle because you've only paid for so much electricity; to say nothing of the usual surveillance, etc).
Experimenting with FLOSS alternatives is an important (but insufficient on its own) hedge against bad manufacturer conduct.
You need root access on the Central Instrument Display of your Tesla Model S or Model X with MCU 2.0 (arm based). Currently only tested on my Model X. I suppose it will also work on the Model S as the architecture is very similar. The latest generation of Model S/X and the Model 3 might be more problematic for now as they use an Intel based board instead of the ARM based Linux system. If someone has root to such a Tesla, we might get FreedomEV working. Aside from root access, we need some kind of 'persistence across reboot'. On the MCU 1.0 and 2.0 cars this is easily accomplished using the crontab as it reads from a read/writeable /var filesystem. Model 3 cars are even better closed down and harder to root. Tesla gives high bug bounties for those people finding root exploits and/or persistence across reboots; thus ensuring everybody their cars are safer. These tools and FreedomEV can help security researchers to better analyse and find potential problems. With root access, FreedomEV can be installed with one command:
freedomev [Jasper Nuyens/Github]
(via Four Short Links)