I'm seriously thinking of using a small inverter for the power brick. Figure I can wire it either via relay or direct to switched power and then set the netbook to power down after 5 minutes of inactivity when on battery power. That way, when the key is turned off, the inverter looses power and the netbook goes to battery. Then it just powers itself down after 5 minutes. Just need to remember to set the power option to something else when I take it out of the car.
Since my car is rather cramped, I'm thinking of getting a touchscreen to mount somewhere. Figure I can set the netbook to "do nothing" when the lid is closed (it does blank the screen). That thing is so small closed that it can be set about anywhere without too much problem. May be able to set it in the glove compartment.
I've already loaded Centrafuse and Roadrunner. Centrafuse nav is having trouble finding the gps receiver coming up from hibernation even with some of the fixes applied. I've never really played with RR but I think it may be better for my purposes.
As far as performance, the Mini 9 is about what I expected. It certainly isn't a rocket but does do well. Signal for wireless is very good. Keyboard takes a little getting used to but is usable. And, considering what I paid for the system in my truck, the Dell is a good buy even if I end up adding a touchscreen. The only thing missing is the am/fm tuner that the truck system has, and that's not bad since reception isn't as good as the head unit.
Overall, I think it was an excellent choice.