The Xi3 booth at CES was jam-packed with these ultra-cool x86 computing systems. Shown above is the Xi3 5A. This 4" modular cube houses a 1.8ghz dual-core AMD CPU, 2GB of system RAM, and up to 1TB of solid state storage. It's modular design allows for a host of peripheral devices, with multiple options for USB/ eSATA, and display ports. The 5A does include a fan for system cooling, but I can say after demoing the device it's indeed silent. It sips power at only 20 watts, and can be powered from 12-24v.
So what's missing from making this a go to Car PC option? The only downside i see is the lack of the smart automotive power management that we know from Opus and Minibox systems, but because the device is modular and Xi3 is looking at the device to be installed anywhere possible, the engineers eyes lit up at the idea of creating a automotive add-on module to handle that. ETA is of course unknown, but it's great that there's another company out there that gets frenzied up for car PC goodies.
If the 1.8 dual core isn't enough power for your setup, Xi3 has other builds that might work. The X7a, while slightly more power demanding at 40 watts, packs quad core power and more memory to boot. It's plenty powerful enough for the user who needs to video edit or game on the go.
The Xi3 modular systems start at just $399.