According to Mythbusters [1] it's almost impossible to wind down the windows in a sinking car after it reaches a certain depth. Much better is to have a window breaker tool. You can have one which doubles as a seat belt slicer too.
[1] https://mythresults.com/episode72
There is (seems to be) no way to quickly spin up an instance for testing for new customers. After completing the order form I received an email stating they will check my address details and only after that complete the order and let me pay.