"car spec" digital inputs and outputs?

Not so much an issue with the outputs, as those can easily be buffered with simple transistors and/or relays.The outputs essentially just to turn things on/off from the empeg. But the inputs need to able to withstand all the car the car can throw at it - ie a "12"V actually anywhere between 8 and 15V with a strong likelyhood of even worse spikes... The signals - at least in my case - would be very simple and slow moving, essentially just if stuff is on or off, not anything like serial communications or such.

/Michael