I saw a BMW i3 on the internet set for a junk auction a while back. It looked badly burned like this. I know it can happen to any EV, but gas cars catch on fire too and can burn quickly without a fire extinguisher. The Li-Ion battery, if it catches fire somehow can go into thermal runaway and can burn a car to the ground. I don't know the point at which the carbon fiber frame catches fire, but it seems to melt to the ground with the plastic body panels. The only thing in the photos that I can even make out are the wheels from the side view photo and the steel that is likely from the electric motor on the left in a back view photo. The aluminum looks like it all melted down in the rear from the back view photo. The timing of how long it took to burn is of interest. Makes us want to put fire extinguishers in the car somewhere.
Does the poster have any of the service records for it? What went wrong in the first instance - dead battery or what - to take it into the BWM dealer? It is a 2016 i3 Rex so it had the smaller battery. These fires usually happen when the LiIon battery is being charged and it overheats. Was the HV battery recently charged by the BMW dealer or the owner? Is the REX charging it while the battery is hot? Was the regeneration recharging the battery? What was the weather like? Extremely hot day? Cold weather? Is the air conditioning compressor working to cool the interior of the car and the battery? If the AC compressor is not working, you might get a battery to overheat in high temp weather.
If something was wrong with the battery, I suspect they were repairing the battery instead of replacing it over the 8 month period with the dealer, but I could be wrong. Did they use proper new components - who made the battery replacement parts versus who made the new parts.
One would want to file a negligence lawsuit and get discovery of the mechanics name, all the records of repair, and depose the mechanic, the service manager, and the owner of the dealership. Another cause of action in the complaint could be intentional/negligent infliction of emotional distress from the fire, if anyone intentionally or negligently caused the breakdown. Some attorneys would take this on contingency but would charge 30-50% of the recovery. Insurance would normally cover the car and sue for the damages from BMW or not. A statute of limitations is running from the date of the accident. It is pretty easy to file complaints on your own in certain states to toll the statute so your rights are reserved.
No indication as to what state this occurred in and what state laws might then be at issue.
This can be a lot of work to sue the BMW dealer and it is not clear that it is worth it.