Nobody said you can't have a T-line in a car. I have built several for car audio. Just don't expect to be putting a pair of 15's or an 18 in one without a huge enclosure. Your 10" driver may work in one, you just need to understand what you are going to end up with. Pretty much all "car audio" T-line enclosures aren't really T-lines, or they are severely miss-aligned... When people realize that the output will be marginally better at best than a sealed alignment, the reality sets in to what they are going to end up with. Also, I am not sure about the T/S parameters of your 10" driver, but it if has a fairly low Qts, it won't work well in a T-line due to it's self-dampening low end behavior. But like I said, I have no idea about that 10" driver... It is just important that you understand what goes into them, that is all.