The concept of an in car computer is not really a new one. All modern cars have a dedicated engine control unit which controls the engine and makes it emissions compliant.

The use of a computer running an in car entertainment (ICE) package is a bit more novel. For many years companies like Pioneer and Kenwood have built double din head units that have sat nav, radio, cd etc. The only issue with these has been the lack of customisation and the speed.

Car Computers as of today tend to consist of a scaled down desktop PC running an OS (windows, linux, mac OS) with a front end to make it user friendly for touch screen use.

Whilst the concept of a carputer is not really that difficult, the execution can be. Some knowledge of vehicle electrical systems is of benefit as is the ability to fabricate!

In my case I started off with a clean sheet, I looked around and decided on a list of components that I wanted. My primary driver wasn’t cost, it was what parts were available within the UK!

So here's my tips for Carputer happiness.

Rule 1: The Screen
Under No circumstances skimp on the screen, if you buy a cheap one then don't expect to be able to read it on a sunny day. This is actually much worse in winter as the Sun is much lower and shines on the screen.

There are a few things to note about screen technologies. There is just plain TFT (cheapest), TMR (halfway house) and Transreflective (expensive), below is a comparison which I got from LinITX. Its pretty obvious which one to go for.

Unless you are on a budget, then get the best one you can afford.

The bit associated with the screen is the touchscreen. Resistive touchscreens are common and I've had no issues with them. If you want to spend a bit more then capacitive touch is the next step up.

The size is important, make sure it is going to fit into your prospective "hole"! There have been many shoe horn attempts I have seen that have looked terrible! 7" is a popular size to go for if your "hole" is double DIN.

An alternative is to get a single DIN unit with a motorized display that folds out. This facilitates a much easier install but is generally more expensive and it has moving parts, moving parts usually means a problem!

Rule 2: Fabrication (of the screen)

This is where life gets messy, you need to find somewhere to install your screen. Most japanese cars have double din sized radio slots and fitting a 7" screen with an appropriate adaptor is fairly straightforward. VAG group cars also tend to have double din holes and fabricating in this area is popular.

In my case (my Toyota Corolla), the hole was double DIN height but much wider, so I ended up custom fabricating my screen into the dash panel. This is not for the feint hearted. I had to hacksaw my €500 screen up and then use some epoxy to get it all together. This was followed by a trip to the paint shop and a spray up. This process took me about 100 hours in total. Click my link for screen fabrication to get some tips.

Rule 3: PC Hardware Requirements

There are a few ways of hooking up the PC in the car, the easiest way is probably to use a laptop and run a VGA cable to the aforementioned touchscreen. This is simple and fairly cheap. Would I recommend this? Only if I wasn't technically minded.

My preferred option would be to have a full PC but in scaled down form. Mini ITX or Pico ITX systems are ideal. They are small and relatively frugal on power. Unless size is an issue, I would go for the Mini ITX due to the availability of motherboards and price. The PICO itx systems tend to be more expensive and have less processing power.

On the subject of processing power, the popular choice at the time of writing is the intel ATOM or variants. These are cheap and have everything on board, just add RAM and away you go. I personally went down the AMD route and installed the fastest processor I could get that had a thermal dissipated power output of 45W. My philosophy is fit the biggest/fastest/strongest one that will fit in the space!

Once the motherboard is picked then the rest of the items that should be considered are GPS (this is a must in my opinion), hard drive, CD Drive (probably not worth it in todays flash drive days), Wifi, Bluetooth, Radio, Case, Power Supply. The majority of these are personal taste and it doesn't really matter which one you go for but I have detailed a few things that should be considered.

Power Supply

Out of all of the components listed above the most important is the Power Supply. Cars were not designed to have all of these high frequency electronic components in them and this leads to a problem. The emission of RF inside what is effectively a faraday cage can lead to distorted sound, poor quality video, inconsistent response on items etc etc. The RF all stems from the Power Supply so make sure you get a decent one! The popular choice is the M2-ATX but this is the worst for RF noise in my opinion so after buying one, I ended up ditching it and bought an Opus instead. In order of preference, i would list it as

1. Opus
2. DSATX
3. Mpegbox Units (M2, M3, M4 ATX)

You can end up in a whole world of pain if you buy the wrong power supply.

Hard Drive
This is a no brainer, solid state every time! moving parts = problem.

Radio
When I built my CarPC I had no idea the issue of radio would be such a problem. I had a good look around the forums and then asked myself the question, how bad could it be? The answer is very bad! I have been through so many radios that in the end I got annoyed and built my own. The problem of RF noise causes AM radio to be totally non-existant and FM to be distorted. In Europe and Australia the solution is to use either DAB or DAB+, the sound quality is perfect and a doddle to install.

My preference of radios is

1. DAB/DAB+ (Obviously mine! 300+ people can't be wrong)
2. Visteon HD Radio
3. Silabs
4. HQCT

Case
The VOOM 2 PC Case was originally top of my list as everyone had one. In hindsight this was a poor choice as its a bit of a pain to get the box to shut properly and its heavy and from a thermal point of view not that great. I have since changed to a jye jou 528, having a case that is easy to work with is a must. You'll probably have the top on and off so many times its a necessity.

Amplifier
PC's will only output line level, these will need to be amplified to drive speakers so an AMP will be required. Any old car amp will do and these days with the advent of class D amplifiers, a cheap and compact one is readily available. Unless you are a total purist, I would purchase a named brand that fits in the space!

Rule 4: Installation

Installing is easy, the problem is getting a reliable install first time. There are a few things that will be required and apart from the obvious such as power! The one that comes back to bite is noise. Car PC power supplies give off noise and it is very important to minimise it. Thus I suggest the use of shielded cables everywhere. Cheap unshielded audio cables will attract noise and you'll end up having to rip the car up to replace them. So its worth shelling out for decent ones first time around.

TBC