vffgaston:
By no means. It is explicitly forbbiden.
Really? It's not life support or automotive. That's what AVR tells you not to use it for in their data sheet:
Unless specifically provided otherwise, Atmel products are not suitable for, and shall not be used in,
automotive applications. Atmel products are not intended, authorized, or warranted for use as components in applications intended to support or sustain life.
Also it doesn't sound exactly forbidden, but if you do it and it goes wrong, Atmel can point to this line to avoid liability claims.