Anyways, from what ive found so far from testing in a true SPL vehcile, its difficult to properly burp your setup via a carputer. It became way too inconvienent to screw with a touchscreen during a run...plus everything in the vehicle was vibrating so much, you couldnt keep your finger on the touchscreen in the right place to start/stop the track your were burping on.
I ended up getting a 50 foot remote for doing burps, and it still became a problem. I also went thru several sound cards and never did find anything I liked, I had the M-Audio USB MIDI interface, the Turtle Beach usb dongle, and onboard audio and all of them were fairly noisey. The one device I found that I did not buy, which i sitll might is the Silverstone DAC usb converter for the audio output. They're only $110 but unfortunately only have 2 volt outputs.. and their tech support people are terrible, I had to teach them about their own product.
I mainly ended up using my carputer as a portable Termlab, which has actually worked out great. I highly suggest this to anyone with a Termlab as it comes in real handy.