I tend to agree with you - but had a customer with a NTG3 that had read somewhere if you go SSD in that it doesn't last long. But its not something I have tried.I get that, but trim is usually for high IOP
workloads with multiple read and writes. For an SSD drive in car used for navigation I fully expect it to be 99.9% read only with only minimal data writes for user metadata such as stored destinations etc.
I would also comment that a spinning traditional hdd has more chance of failure in a car than an SSD drive regardless of flash fatigue.