Automotive Lighting Control Module I am looking for an Arduino-based solution for an automotive lighting application.

System Requirements:


Able to Operate in Automotive (Interior) Environment (12 +/- 2V DC    Voltage)
Minimum 3 12 V DC Inputs (Preferably 6)
Minimum of 3 12 V DC Outputs capable of operating standard automotive-style 
relays. (Preferably 6)
Compact/Condensed Form-Factor


Finding an Arduino that runs on a 12 V power supply is simple, but finding one that can handle 12 V I/Os has proven tricky.

Using a relay shield for the outputs is straightforward enough, and would be a safe way to step up the output voltage and current (although current is of little concern, given I'm only going to powering the coil in a relay). But what to do about the inputs? I don't want a transistor on each input - that would get quite tedious and large very quickly. Using relays on both sides would work, but most shields are setup to receive coil activation signals from the Arduino and as such also can't handle 12 V inputs, so using a relay shield to step-down from 12 V to 5 V also seems problematic.

Is there an all-in-one I/O solution that can step-down incoming voltages for the board and step-up output voltages on the other side?

What are my best options? I'd prefer not to have to custom-make a shield for such a basic I/O application...

Any and all help is greatly appreciated!
A Logic Level Converter can step-down incoming voltages for the Arduino inputs and may also work to drive the relay coils. Heres an example of a 4 channel board: 

https://www.sparkfun.com/products/12009

and there are also 8 channel boards:

http://www.ebay.ca/itm/8-Channel-I2C-IIC-Logic-Level-Converter-Module-Bi-Directional-for-Arduino-MF-/172424799119?hash=item282551a38f:g:6Q0AAOSwo4pYPDwg.

The boards are small and use BSS138 MOSFETs, which, according to the data sheet: http://cdn.sparkfun.com/datasheets/BreakoutBoards/BSS138.pdf can handle a maximum of 0.22A continuous current and a Drain-Source Voltage of 50V. The SparkFun link has lots of information about these devices. Normally, you would use them to translate between 5V and 3.3V but I don't see why you couldn't power the "high voltage side" with the vehicles 12 - 14V and the "low voltage side" with 5V from the Arduino.