Got side tracked and couldn't finish my original post.

Here's the case I'll be using. It's a brand new Lian Li prototype. I think it's made designed as a HTPC case because it looks so nice, but I'm going to tweak it a bit for in car use.

This high quarity case is made out of the finest materials. I had to break out my $1.99 Harbor Freight scissors to cut through it. It's steel, not aluminum.

Test fit. This thing's going to look sweet!!!

Awe, a masterpiece!!! This thing would look great integrated with the finest home audio gear. It's a shame it will be hidden under my seat.
Okay, enough flaunting of my equipment, back to the review.

The ATX PSU that came with this case puts out a rock solid 12ish volts.

Here's a test run with just the motherboard and hardrive hooked up on my laboratory workbench. The M2-ATX is being powered by the old ATX PSU. Due to this motherboards layout, the wire that goes from the M2-ATX to the "on" switch on the motherboard is way to short. The directions are fairly clear if your wiring this PSU up to your car, but nothing is said about testing it on the bench like this. I googled how jump the ATX PSU into working and then just started connecting M2-ATX wires randomly until the pc powered up. I insulated the back of the M2-ATX from the pc case with professional electricians grade paper envelope.

This one's kind of messy. I have the same setup as above with an ampmeter between the ATX PSU and the M2-ATX. I've also added a CDRW drive. All the system components are being powered by the M2-ATX. It's only pulling about 4.8A (58 watts, I guess) in the picture, but I'll soon fix that. I moved the envelope so the M2 wouldn't get too much insulation.

I overclocked the P4 Northwood cpu from 1.8 to 2.4 and bumped the voltage from 1.5-1.7 to try to draw more power. I saw the meter hit 9.2 during Windows installation, but his was as high as I could photograph. I guess I'm up around 110W. So far the M2-ATX hasn't missed a beat and I haven't noticed any serious heat issues.
I know from the photos, it probably looks like I'm a professional and do this stuff for a living, but I actually don't really have a clue what I'm doing. I'm not even sure if my ampmeter is hooked up correctly, but the readings seem about right, so it's probably okay. I suppose I'm probably supposed to be measuring some voltages and stuff too. Feel free to help me out people.
Next, I'll test out the startup/shutdown controller functionality on the bench, but I'm pretty lazy, so don't expect to actually see it in my vehicle for a few weeks. After that I'm going to go dig up as much **** as I can find to plug into this system and see what this power supply can really do.
So far I'm impressed with the unit, but I'm using a laptop in my car now, so I don't have any reference to compare it too. It's been sitting on my static filled carpet for a week, I've dropped it on the ground once, and have rolled my chair wheel over it (as I stood up, so my weight wasn't on it). It still looks and works fine.
Pros:
Great build quality.
Stable performance with desktop components.
If I haven't broken it yet, it's unlikely that you will.
Cons:
Lack of P4 motherboard power cable.
Motherboard switch wire way too short.
Documentation could be improved; people like me need more detailed directions.