PETG works for cars. This summer tested in Spain, i have printed a holder for the mobile.

I have a digital temp controller oven so i have found that yes, 75C is the temp that the PETG starts to lose rigidity and is able to be reshaped. But one very important thing to understand is that in an oven 75C means the whole piece is heated from all sides so there is no way to cool. While in a car it could be only partly heated or one side heated. So its not the same. In reality i expected a fail but that was the only material i had at hand at that moment
PETG will work also for printer parts inside enclosure, as the desired and achieved in reality temperature of the enclosure is around 40-45C, no more.

But PLA is definitely a fail in the car dashboard or directly hit by sunlight here in Spain. neither it works for printer parts in enclosure.

Hi Temp PLA is absolute crap. tried all the famous brands. Heat treated and so on. No, no and no. Very difficult material. Once you try to treat it it warps tremendously >5% so is unusable in real life.I have f%%d at least 50 pieces but to no avail. So i stopped using it.

So heating to certain temperature in an oven is not the same as in normal use. But FYI under the car hood is an oven so there only Nylon and at worse case ABS. maybe PEEk also.