First excuse me for my miserable English...
I am quite new to carpc stuff. I am still in the planning stage of my carputer, however I have one concern when considering the heat dissipation of a carpc. In my experience the inside of a car is always full of dust no matter how often I clean it and a computer is always a dust catcher due to static. Therefore a carpc is likely to quickly filled with dust, increasing the danger of short circuit/damaged motherboard (It happened few times when I work with desktops), I thought about few solution of this issue but non of them is perfect, I list them out and hoping someone can give a perfect solution or a successful story.
1. use a fanless design(i mean no case fan, too)
Use a fanless design seems to decrease the chance that computer catches dust. However there still two concerns. First the appearance of a carpc is hard to blend with the interior trim, so it is likely to be hidden inside dash(or somewhere else) where venting is not very good, making it difficult to have a stable fanless solution. Second during summer time the inside of the car can become extremely hot, the CPU may freeze/auto off before the AC can cool the temperature down.
2. use a design with a fan and filter
This is what I usually do with desktops, and here's a small tip: Instead of expensive filters specially made for computer, 2 pieces of used dryer sheet did the trick... The problem comes because the filter need to be changed regularly. It will be a pain if I need to disassemble my dash, pull the carpc out and change the filter.