Wow! Could have happen to me.. 1U open car park quite raised up. The bus terminal is at an even lower level, if that flooded, the lower ground car park also flood lor?
If car just submerge, without engine running. Very important to cut the battery supplies. E90 easy because got a big fuse terminal slap over the battery, I think can shut the power from there rather than removing terminal which require a size 10 wrench. Normally car suffer from this need to replace all fluids and that alone, no less than RM2k, before attempting to crank the engine again.
If car is driven over still water/flood and engine die, Opps! piston would have seized because water may have sucked into the combustion chamber through the air filter inlet. con rod can bend, piston can break into pieces, cam shaft can twist.
Anyway, good luck!
Normal insurance do not cover such act of nature, unless u buy separately. Can try claiming from MPPJ or the building management. My friend's MPV was hit by a falling tree on Jalan Sultan Ismail, in front of Sheraton Hotel, he managed to claim from DBKL.