Just what coppice said.
There is much more to automotive qualification than just temperature!
If you intend to release a product to market, it will have to get certified one way or another, even if it's a gadget - then it would be auto-certified (meaning that you take the whole responsibility, by the way). You have to assess what the potential risks of a failure are. If you are 100% certain that no harm whatsoever either to the vehicle or to its passengers can be a consequence of a failure, then fine. You can use industrial or even commercial-grade components.
Just remember that even if the product is not directly safety-related, it may compromise safety in some cases: let's take a very simple example and say your device fails and catches fire as a consequence. If this device is clearly marketed for automotive use, then you might get into a lot of extra legal trouble if you didn't use automotive qualified parts unless you have documented a very solid reason why you didn't and additionally can prove that it wouldn't have made a difference. Not necessarily trivial.