here was my method:
i found that not every time i was able to total the fire truck (to the point where they automatically jump out). sometimes it gets so damaged that it just slows down making it hard to further crash.
i just found a fire station with a fire truck (the one on east melrose) and kept crashing to the point where it slows down. i did this 10 times and ended up with ~ 65,000 worth of damage.
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