How about a sticky where people post what types of cars (ex. dsm, honda, nissans, etc.) so people know who to ask for help?
How about you fill out your profile with your car type and people just click that? 
Most people have their cars in their sig anyway.
Besides, some people are good with more than one car. Just post your questions in tech and somebody will see it.
You mean just like this thread?
http://www.nyspeed.com/forums/newreply.php?do=newreply&p=111189
oh yeah add two more nissans to my list…