Would be nice to have a page full of forum posts like this for various cars. Incidentally, this link recommends termination resistors, which I think are the be

Would be nice to have a page full of forum posts like this for various cars. Incidentally, this link recommends termination resistors, which I think are the better answer if there's a suitable connector (which I imagine is the case for most cars). If it's not terminated, I believe it can still pick up a nontrivial signal.